A. E. Verrill — Marine Nenierteaiis of New England, etc. 389 



II. Only two distinct groups of ocelli, anterior or sub-lateral ; cerebral 

 groups obscure or wanting. — Cosmocephala Stimp. 



2a. Only anterior groups of ocelli are evident. 

 A. frontalis V., sp. nov. 



2b. Only median lateral groups of ocelli are present : or else the 

 median and cerebral groups are blended. 

 A. mesosorusY., s]!. nov. 



III. Ocelli form only elongated lateral rows more or less parallel with the 

 sides of the head ; cerebral groups are not distinct from tlie others. 

 Body slender. — Ophionemertes Verrill. 



A. cruentatus V. 

 A. virescens V. 

 A. agilis V. 



IV. Only a single pair of anterior ocelli are present.--Z)ic7i//MS Stimj:). 



A. bioculatKs Mclnt. 



V. Ocelli indistinct or absent. — Naredopsis Verrill, sub-gen. nov. 



A. caucus v., sji. nov. 



VI. Ocelli doubtful, forming at least a pair of antero-lateral groups (per- 

 liaps others that are not observed). 



A. thallius V,, sp. nov. 



VII. Cerebral groups of ocelli (?) alone observed (perhaps anterior ocelli 

 overlooked). — Nareda Girard. 



A. superbus (Gir.) 



AilPIIIPORUS. 



Analytical Table of s-pecies based ox the arraugeniod of the ocelli. 



A. Ocelli present. 

 B. Ocelli numerous, arranged in groups. 

 C. Ocelli arranged in four groups ; two cerebral, near the ganglions, 

 and two anterior or antero-lateral. 

 D. Anterior clusters of ocelli transverse, at the front margin of the head ; 

 posterior groups roundisli. 



a. Anterior groups transversely oblong or partly double. A. angidafus. 

 aa. Anterior groups each divided into three subordinate clusters. A. mal- 



tisorus. 

 DD. Anterior clusters are not transverse at the front margin. 



b. Anterior clusters subdorsal, not parallel with the margins of head. 



c. Anterior clusters are triangular with the acute angle backward. ^4. het- 



erosorus. 



cc. Anterior clusters are oblique I'ows parallel with the posterior ones. A. 

 tetrasorus. 



bb. Anterior clusters lateral or sublateral, curved or crescent-shaped, ante- 

 riorly partly parallel with the margins of head. 



e. Posterior groups forpi round or angular close clusters. 



/. Anterior groups are large, composed of several rows posteriorly, and 

 nearly blend with posterior groups. A. roseus. 



