A. E. Verrill — Marine ISfemerteans of Neio England, etc. 387 



Amphiporus Ehrenberg, 1831, Mcintosh, non Dies., nee CErsted. 



Oinmatoi)lea khr., Symbohe Physicse, 1831. 



Omato'pka Diesing, Syst. Helm., vol. i, p. 248, 1850. 



Polystemma Khr., 1831 ; (Ersted, Naturhist. Tidssk., iv, p. 579, 1844. 



Polia Quatr. (pars), Ann. des Sci. Nat., vi, p. 201, 1846, non Delle Chiaje, 1841. 



Cosmocephala Stiinpson, Prodromus, in Proc. Acad. Nat. Sci., Philad., vol. ix, p. 



165 [21, aep. copy]. 1857. 

 Folina Stimpson, op. cit., p. 165. 

 OpMonemertes Yerrill, Amer. .Journ. Sci , vol. vii, p. 45. 1873 ; Proc. Araer. Assoc, 



1873, p. 389, 1873. 



Body only moderately elongated, in some species slender, in 

 others stout ; usually strongly convex dorsally and with rounded 

 sides. 



Head often distinct from the narrowed neck, but in other cases 

 of the same breadth as the body and without any definite limita- 

 tion. 



Transverse or oblique ciliated fossje or shallow grooves, two of 

 them connected with the ciliated sensory ducts, are, apparently, 

 always present, though often very indistinct; usually there is a pair 

 at the back of the head and nearly in line with, or just behind, the 

 posterior ocelli and the ganglions; the other pair, situated in front 

 of the ganglions, is usually less distinct and may be easily over- 

 looked, and is perhaps absent in some species. One or both pairs 

 of foss?e may meet on the dorsal line in certain species. 



Ocelli usually numerous, variously arranged ; perhaps the most 

 common or typical arrangement is that of two anterior groups and 

 two posterior or cerebral clusters, but either pair may be lacking, 

 or the two groups may blend, and sometimes no ocelli are visible. 



Proboscis-pore terminal, or sometimes sub-terminal, just under 

 the tip of the snout. Proboscis large and long. Central armature 

 a simple, sharp stylet with thick base ; lateral stylet-sacs usually 

 two, each with two to four, or more, pin-shaped stylets. 



Mouth far forward, usually united with the proboscis-pore, and 

 therefore not visible in contraction. 



The numerous species belonging to this genus* were distributed 



* Many authors, of whom a few are indicated in the synonymy, have used Omma- 

 toplea Ehr. as the name of this genus, and on many accounts it seems to'me that it 

 wo\ild have been better to have continued that usage. Mcintosh, in his rnonograpli, 

 has, however, seen fit to change the name to Amphiporus (of tiie same date) for 

 reasons that are. to say the least, of questionable validity, — mainly because somebody 

 may hereafter discover that the " type " of Ommatop)lea is of a different genus, though 

 he gives no reason for supposing that to be the case. In this instance long usage 



Trans. Conn. Aoad.. Voi.. VIII. 51 .Thne, 1892. 



