formis) but the degree of complexity of plan of structure is absolutely uniform throughout the group. The only apparent exceptions to this rule are the best proof of the rule. Twenty-seven of the species are strictly of the sort described. The species called Disholcaspis weldi, D. centricola, D. douglasi, D. maculipennis, D. brevipennata, D. arizonica, and D. truckeensis produce galls which are very different from typical galls of Disholcaspis, but none of these species really belong to this group. The adults of the species brevipennata, centricola, maculipennis, and weldi have parapsidal grooves extending to the pronotum (not quite entire in weldi), have the second abdominal segment “tongue-shaped,” i. e., produced dorsally, and in other ways are generically different from the species belonging in Disholcaspis, which genus was correctly limited by original definition to formns having the parapsidal grooves extending only to the middle of the mesothorax and the posterior edges of the second segment of the abdoinen perpendicular or nearly so. Mayr (1902) very properly removed centricola and douglasi to the genus Dryophanta, with some of the species of which genus they have evident relationship; and there is as good reason for removing from Disholcaspis the other species listed above. Again, arizonica, which is apparently unknown except from the type material which I have not seen, is the only species included in Disholcaspis which has fifteen-jointed antennæ, and was first described (for reasons not evident from the description) as “closely related to Cynips sulcatus Ashmead, but differs by its much darker colour and infuscated wings. It seems to go best in Holcaspis” (Cockerell, 1902, p. 183). If this species differs from Cynips sulcatus mainly in color, it certainly does not belong to the genus Disholcaspis. Finally, truckeensis has the parapsidal grooves extending to the pronotum (only half as long in true Disholcaspis), has the cheeks almost as long as the compound eyes (only half as long in true Disholcaspis), and I have obtained it in both sexes (Disholcaspis is entirely agamic). That is, none of the apparent exceptions are truly exceptions to the rule of the uniforinity of degree and sort of complexity of the galls of this genus. And such complete uniforinity is not very likely mere coincidence but must be truly significant of the genetic relations of the insect producing the gall.
Reproduction in Disholcaspis must be entirely agamic. No males have ever been bred from or found in the galls of this group.
Whether alternation of generations occurs in Disholcaspis, with possibly bisexual reproduction in an alternate generation, is not definitely known. The genus is confined to America, so European workers have
