Great Spangled can be ruled out because this specimen was medium sized, not large, and the wing pattern (above and below) does not remotely resemble Great Spanged Fritillary (see p. 136, Glassberg/p.158, Brock).

Great Basin Fritillary can be "confusingly variable" (p. 146, Glassberg). It may resemble Atlantis (Northwestern), Coronis, Zerene, Callippe, and Mormon Fritillaries (ibid.). It is usually found at higher elevations "in openings of mixed or coniferous forests" (ibid.). Forewings are slightly pointed (Brock), but this trait is still too subtle to be useful to me. Some of the photographs found in Glassberg and Brock strongly resemble this individual. However, Crabtree in his book, "Discovering the Butterflies of Lassen Volcanic National Park," p. 39, states that the Great Basin (Egleis) Fritillary, while being the most common fritillary in the park, is also one of the smallest. This individual, though not as large as Coronis, could not be described as small. Crabtree also states that the lower hind wing is tan with silver spots. The lower hind wing is reddish-orange, not tan, and the spots are unsilvered. Conclusion: not a Great Basin Fritillary.

Mormon Fritillary is said to be small, similar in size to a lesser fritillary (p.144, Glassberg), this individual was medium sized. Mormon Fritillaries prefer wet meadows (ibid.); this specimen was in a dry meadow. Forewing veins on Mormon Fritillaries are "black and thin" (p. 160, Brock); this specimen has relatively thick forewing veins. Also, Crabtree does not mention Mormon Fritillary in his book, which I assume is an indication that it has not been found in Lassen Park. Conclusion: not a Mormon Fritillary.

On Callippe Fritillary, the "median and submarginal pale spots show through the wings above." The pictured specimen does not exhibit this character. Also, the marginal pale spots on ventral hingwing are oval, not triangular as is usual for Callippe (p. 144, Glassberg). Also, Crabtree (p. 39) states that Callippe (aka Nevada Fritillary) occurs near the park but has never been found in it. Conclusion: not a Callippe Fritillary.

Coronis Fritillary is described by Crabtree (p. 39) as being "slightly larger and lighter colored than either Zerene or Hydaspe Fritillaries . . ." and as having ". . . upper wing surfaces . . . yellowish orange . . . [and] underneath, having large silver spots." I saw a number of Coronis Fritillaries on the Brokeoff Mountain trail this past Sunday, July 8. They were noticeably larger and paler (above) than this individual with large spots very silvered. Conclusion: not a Coronis Fritillary.

Northwestern (Atlantis) Fritillary is not mentioned in Crabtree's book, and I therefore assume it does not occur in the park.

(This paragraph covers Zerene and Hydaspe.) Zerene Fritillaries from the Sierra Nevada/Cascades eastward, according to Brock, p. 164, have silvered spots and westward, they may be silvered or unsilvered. In short, Brock isn't very helpful here. Crabtree, p. 39, says Zerene are "a deep orange-brown above and a dull brick red underneath." This indvidual fits that descrition pretty well. Brock shows the Sierra Zerene's as having noticeably smaller post-median spots on the hind wing than Hydaspe. This individual has quite large post-median spots on the lower hind wing. However, the photographs in Glassberg, p. 142, do not support Brock in this regard (in Glassberg, Zerene has quite large post-median spots). Glassberg states that Zerene has "very strong wide FW median spots." This individual has such. Glassberg also says that "the outer edge of the post-median spotband appears to be smoothly coherent [on Hydaspe]; more jagged and less coherent on Zerene." Looking at the photographs in Brock and Glassberg, I would say this individual looks more like Zerene in this character, i.e., "more jagged and less coherent." Conclusion: probably a Zerene.