166 HINTS ON THE ANCESTRY OT?- INSECTS. 



their strange /onns. From the nou-segineuted, sac-like larva, 

 it passes directly into the pnpa state. 



The last egg-parasite noticed by Gauin,' is Teleas, whose 

 development resembles that of Platygaster. It is a parasite in 

 the eggs of Gerris, the Water Boatman. Figure 197 ^-l repre- 

 sents the egg; B, C, and D, the first stage of the larva, the 

 abdomen (or posterior division of the body) being furnished 

 with a series of bristles on each side. (B represents the ven- 

 tral, C the dorsal, and D the profile view; at, anteunai; vul, 

 hook-like mandibles; mo, mouth; b, bristles; m, intestine; aw, 

 the tail; ul, under lip or labium.) In 'the second larval stage, 

 which is ov'al in form, and not segmented, the primitive band 

 is formed. 



In concluding the account of his remarkable discoveries, 

 Ganin draws attention to the great differences in the formation 

 of the eggs and the germs of these parasites from what occurs 

 in other insects. The egg has no nutritive cells; the formation 

 of the primitive band, usually the first indication of the germ,, 

 is retarded till the second larval stage is attained ; and the 

 embryonal membrane is not homologous with the so-called 

 "amnion" of other insects, but may possibly be compared with 

 the skin developed on the upper side of the low, worm-like aca- 

 rian, Pentastomum, and the "larval skin" of the embryos of 

 many low Crustacea. He says, also, that we cannot, perhaps, 

 find the homologues of the provisional organs of the larvje, such 

 as the singularly shaped antenna3, the claw-like mandibles, the 

 tongue- or ear-like appendages, in other Arthropoda (insects 

 and Crustacea); but that they may be found in the parasitic 

 Lerna3an crustaceans, and in the leeches, such as Plistriobella. 

 He is also struck by the similarity in the development of these 

 egg-parasites to that of a kind of leech (Nephelis), the embryo 

 of which is provided with ciliffi, recalling the larva of Teleas 

 (Fig. 197 B, O), while in the true leeches (Hirudo) the primi- 

 tive band is not developed until after they have passed through 

 a provisional larval stage. 



This complicated metamorphosis of the egg-parasites, Ganin 

 also compares to the so-called " hyper-metamorphosis " of cer- 

 tain insects (Meloe, Sitaris, and the Stylopidie) made known by 

 Siebold, Newport and Fabre, and he considers it to be of the 

 same nature. 



He also, in closing, compares such early larval forms as those 



