408 



PROr. a. GILSON ON SEaMENTALLT DISPOSED 



ventral face, through a very small opening, no spinneret-like 

 organ existing on these two segments. The aperture is ex- 

 tremely difficult to detect from the exterior, even with the help 

 of good lenses, on account of its lying either inside or on the 

 very edge of a deep cuticular fold. 



Fig. 1. — Phryganea grandis. Dissection (dorsal aspect). 



g^, g"^, q^. Thoracic glands, 



sg. Silk-gland. 



m. Muscles. 



oe, CEsopliagus. 



md. Mandibles. 



In other species, for instance in LimnopMlus flavicornis, the 

 prothoracic gland is alone represented, and (c/. fig. 2) this single 

 gland ditfers considerably from that of Phryganea grandis. It 



