NEOMENIID. 347 
and (. strigatus, Sowb., which are figured as without pores. In 
the former the valves are separated, in the latter they touch. 
The species need examination to confirm the accuracy of the 
figures, but it is probable that there are both poriferous and 
not poriferous. ‘ 
Famity NEOMENIID A. 
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. 
NeomentA, Tullberg. 
Syn.—Vermiculus, Dalyell. Solenopus, Sars. 
Distr.—5 sp. Norway, Mediterranean. 
Sexes united; no tentacula, no eyes, 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 cylindric, 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. 
Orper NUCLEOBRANCHIATA. 
Pelagic animals swimming by means of fin-like lobes of the 
foot; with or without shells, the latter being transparent, glassy. 
The respiratory 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 cylindrical, and the 
tongue armed with recurved spines. The alimentary canal of 
