20 



GENERAL FEATURES, METHODS, ETC. 



hal^its or an adaptation for a life in the bottom ocjzc. In Chaetoderma the ali- 

 mentary tract is a comparatively simple tul)e passing directly through the body, 

 (as with other Solenogastres), ]iro\'itle<l with a ratlula, reduced to a single median 

 tooth, and a voluminous unilobed liver. In other genera (Prochaetoderma, 

 Limifossor) of the family the radula is of large size, and is typically formed and 

 placed. In the Neomeniina this system is more com]ilex. The first division 

 of the digestive tract, which may be termed the atrium, probably corresponds 

 to a highly modified buccal plate, and though usually connected with the mouth 

 (Diagram p. 20, A) may be separated from it. The walls are modified into 



Diagrams illustniting struolure of a iieomenian. .-V anterior end. b brain; dsg dorsal salivary 

 gland; f foot; gon gonad; im, om inner and outer atrial ridges enclosing the cirrose area; int stomach- 

 intestine; s subradnlar organ; sg ventral salivary gland. B posterior end. cl cloacal cavity; cp dorsal 

 limb of gonoduct; do dorso-terminal sense organ; pcm pericardium; r seminal receptacle; sgl ventral 

 limb of gonoduct or shell gland. 



ridges and cirri, ]irobably sensory structures. A radula is generally jiresent 

 though often greatly reduced in size. In addition to the dorsal salivarj' glands, 

 proljably existing in certain Chaetodermatina as well, a ventral pair is usually 



