NEOMENllD^. 347 



and G. strigatus, Sowb., which are figured as without pores. In 

 the former the valves ai'e separated, in the latter they touch. 

 The species need examination to confirm the accuracy of the 

 figures, but it is probable that thei'e are both poriferous and 

 not poriferous. 



Family NEOMENIIDJE. 



The characters of the family are derived from those of the 

 principal genus. It is one of the lowest forms of mollusks, 

 being without many of the organs typifying its order. 



Neomenia gorgoniophila^ Kowalewsky, creeps somewhat like 

 Nemertes ; it sometimes leaves the water, and advances on a dry 

 surface until it dies by exsiccation. When stopped by an 

 obstacle, it creeps backwards. 



Neomenia, Tullberg. 



Syn. — Vermiculus, Dalyell. Solenopus, Sars. 



Didr. — 5 sp. Norway, Mediterranean. 



Sexes united ; no tentacula, no ^es, no radula, no jaw, no 

 shell ; body more or less worm-shaped ; foot long, narrow, 

 entirely hidden by the mantle ; gills at the hinder end of the 

 animal, retractile ; heart rather developed ; body-cavity entirely 

 filled with entrails ; generative organs situated along the back, 

 above the stomach and intestine ; nervous system composed 

 •mainly of a suprapharyngeal circle, with cerebral ganglion, and 

 of two pedal ganglions. 



Proneomenia, Hubrecht. 



Distr. — P. Sluiteri, Hubrecht. Nova Zembla. 



Body c^dindric, calcareous spicula of the epidermis enveloped 

 by a very thick cuticle. A small radula, and distinct salivary 

 glands. A gland near the vent, at the hinder end of the animal, 

 is considered to be the organ of Bojanus. The lateral glands 

 described by Tullberg are probably oviducts. The glands on 

 both sides of the vent seem to be analogous to a byssal gland. 



Order NUCLEOBRANCHIATA. 



Pelagic animals swimming by means of fin-like lobes of the 

 foot ; with or without shells, the latter being transparent, glassy. 

 ■ The respirator}^ and digestive organs form a sort of nucleus on 

 the posterior part of the back, whence the name. 



The abdomen, or visceral mass, is small, whilst the anterior 

 part of the body (or cephalo-thorax, M. Edwards) is enormously 

 developed. The proboscis is large and cjdindrical, and the 

 tongue armed with recurved spines. The alimentary canal of 



