400 Miscellaneous. 



first and seventh arches; on the others the fringes are developed 

 from the outer and convex portion of the arch, and are not at first 

 I)rolongations of the internal gills. 



(6.) The nostrils, as in all Vertehrates, consist at first of pits or 

 indentations in the integuments ; secondly, a lohe is developed on 

 the inner border of each ; and, finally, the two lobes become con- 

 nected, and thus form the homologue of the fronto-nasal protu- 

 berance. The transitional stages of these correspond with the adult 

 conditions of them in other species of Selachians. 



(7.) The nasal grooves arc compared with the nasal passages of 

 air-breathing animals, and the cartilages on either side of these to 

 the maxillary and intermaxillary bones. 



(8.) The foremost part of the head is formed by the extension of 

 the facial disk forward. While this extension is going on, the cere- 

 bral lobes change their position from beneath the optic lobes to one 

 in front of them. 



(9.) Two anal fins, one quite large and the other very small, are 

 developed, but both are afterwards wholly absorbed. 



(10.) The dorsals change position from the middle to the end of 

 the tail. At the time of hatching, however, there is still a slender 

 terminal portion of the tail, which is afterwards either absorbed or 

 covered up by the enlarged dorsals, as they extend backward. — 

 Memoirs of the American Academy, vol. ix. pp. 31-44. 



On Dimorphism in the Hrjmenopterous Genua Cynips. 

 By Benjamin D.Walsh, M.A. 



The Cynips studied by Mr. Walsh make galls on a species of oak, 

 the Quercus tinctoria. Part of these galls produce males and fe- 

 males of the Cynips spongijica in June. Another portion of them, 

 of wholly similar general character, remain green till autumn, and 

 produce in October and November, and also in the following spring, 

 another form of Cynips — the Cynips aciculata, hitherto regarded as 

 a distinct species, all the individuals of which are females. Mr. 

 Walsh appears to prove that the latter, although widely different in 

 many characters, is only another form of the C. spongificu, and 

 thence that this species is dimorphous. The individuals produced 

 in June live but six or eight days ; what place in nature, then, tlie 

 author asks, is filled by the C. aciculata 1 In reply, he suggests, from 

 the analogy of Apis, Bomhus, &c., that " the female aciculata gene- 

 rates galls, which produce by parthenogenesis male sponyifica, and 

 that the females and males of the latter, coupling in June, oviposit 

 in the same month, in the young buds of the oak, eggs that remain 

 dormant till the following spring, some of which then produce /e/«a/e 

 sponyifica in June and some female aciculata in the autumn or early 

 in the following spring, and these last, in their turn, generate male 

 sponyifica to appear in the following June." He continues, " It may 

 also be the case that some few male sponyifica are generated by fe- 

 male sponyifica.'" The author next sustains this opinion by men- 

 tioning some of the analogies that have been observed in other 

 Hymenopterous insects. — Proceedinys of the Entomoloyical Society 

 of Philadelphia, March 1864, pp. 443-500. 



