OF OECANTHUS AND TELEAS. 263 



it arises from the large " central cells," which at first constitute a solid cylinder, in which 

 a central cavity is afterwards developed. The proctodaeum and stomodaeum arise here, 

 as in the other Pteromalidae, by invaginations of the hypodermic layer at either end of the 

 body. The earliest stage observed by Ganin was what he called the first larval form. It 

 bears a very strong resemblance to the first larva of Platygaster ; the cephalo-thoracic por- 

 tions especially are to be compared. The only internal organ possessed by this larva is a 

 mesenteron which ends blindly behind. Its wall is composed of comparatively large cells, 

 and is destitute of a muscular layer. The cuticular covering of the body is furnished with 

 two sharp, curved jaws, an upper lip (located far back of the mouth openino- near the 

 junction of the cephalo-thoracic with the abdominal portion of the body), a tail and two 

 transverse rows of bristles back of the head region, one on each side of the body. These 

 bristles are structureless prolongations of the cuticula and are long enough to reach to the 

 end of the tail. The author observed them in motion but could not distinguish the muscles 

 described by Metschnikoff. The tail is composed of two conjoined parts and diminishes 

 constantly in size with the growth of the larva. On the transition to the second larval 

 stage it disappears. The thin, structureless cuticula is thickest on the head. On the ven- 

 tral side of the latter is seen the mouth opening, circular in form. It lies in the median 

 line between the jaws and is bordered by a sharp outline. The proctodaeum does not 

 appear in the first larva and the muscular system remains but poorly developed. There 

 are a number of tail- and jaw-muscles. The body cavity contains numerous amoeboid cells 

 which are believed to be the indifferent embryonic cells left from the central cell mass 

 after the formation of the mesenteron, although in Platygaster similar cells are claimed to 

 arise from the hypodermis. In Teleas the latter is of uniform thickness at all points of 

 the surface. When the first larva passes into the second larval stage the hypodermis in the 

 tail region is invaginated and forms a proctodaeum as in Platygaster. It then thickens 

 along the whole ventral line and forms a germinal band which is continuous posteriorly 

 with the undifferentiated walls of the proctodaeum. This process is the result of a rapid 

 cell proliferation in this region. In the dorsal part of the head region the germinal band 

 curves into a pair of very thick head folds which are separate from each other as well as 

 from the hypodermis of the dorsal region. The folds give rise to the supraoesophao-eal 

 ganglia. The lateral portions of the germinal stripe furnish the muscular system. Sali- 

 vary glands appear at first as solid cords of cells derived from the anterior portion of the 

 germinal stripe. They subsequently develop a central lumen, ending blindly behind but 

 opening out in the mouth region. The eggs of Teleas are very small, transparent, and 

 colorless; they possess no yolk. 



These are the main facts which the author gives with regard to the development 01 

 Teleas, he, however, believes on grounds of relationship and for a priori reasons that the 

 development of Teleas corresponds in all essential particulars with the facts obtained in his 

 researches on Platygaster, Ophioneurus, and Polynema. He states that the embryonic 

 membrane which he has called amnion is not homologous with this membrane in other in- 

 sects but is to be 1 compared with the skin developed on the dorsal side of some low worm- 

 like Acarians (Pentastomum) and the larval skin of crustacean embryos (loc. cit., p. -44:6). 



In order to avoid confusion it will be necessary to observe, that Ganin's first larva of 



1 Packard (35) says: "may possibly be." 



