650 A. E. Verrill — Turbellaria, Nemertina, and 



The lower jaws are rather less bent than in the preceding species^ 

 with the posterior ends more incurved and acute. The upper jaAvs, 

 which have about 16 plates in each series, are stronger and more 

 bent in the middle, the anterior plates having the denticles shorter 

 than those farther back and less claw-like than in the last species. 

 The two middle denticles are much the larger. 



The only specimen (probably young) has 55 setigerous segments ; 

 length, V"^"'; breadth, l"""!. 



These two sjDecies appear to be quite distinct from S. pallida 

 Ver., 1873 {non Langerhans, 1879),* and other species of the United 

 States coast, and from S. rubra (Q^rst. and Grube), as Anisoceras 

 (1854) of St. Croix, the only related species described from the West 

 Indian region. f 



In both of our species the lower series of plates of the upper jaws 

 terminate posteriorly in a rather short, irregularly oblong plate, 

 without denticles, while the denticles increase in length on the other 

 plates, anteriorly. Thus the structure is quite unlike that of the 

 jaws in S. rubrovittata figui-ed by Ehlers, but more like that of 

 S. TtudolpMi. The under jaws, especially, resemble those of the 

 latter in form and in having a divergent series of small plates in line 

 with the acute anterior ends, while those of S. rubrovittata 2iVQ much 

 stouter, straighter, and have obtuse anterior ends. 



It is possible that these two Bermuda forms may be male and 

 female of one species, but our specimens appear to be immature and 

 the sex cannot be determined. Should this be the case, the name 

 n\elanops would be preferred. 



Stauronereis polydonta, sp. nov. 



A third species has much longer upper jaws, with about 35-40 

 l^lates in each row, gradually decreasing to the minute anterior ones. 



* For the species named (S. pallidus by Langerhans, 1879, I propose the name 

 Stauronereis Maderice. It is very different from our New England species. 



f The curious free-swimming, gregarious species recently admirabl)' described 

 and illustrated by A. G. Mayer (Bull. Mus. Comp. ZooL, xxvi, No. 1, with 3 

 plates, 1900) as Staurocephalus gregarious, does not really belong to that genus, 

 but is the type of a new genus for which I propose the name Mayeria. 



This genus is characterized by the presence of a single pair of unsegmented 

 organs (palpi) on the front of the head, and by the unsegmented dorsal cirri. 

 The type is without antennae and eyes. The jaws, also, differ considerably 

 from those of tyjiical Stmirocephahis. 



Mayeria gregarica, the type species, was found swimming at the surface off 

 the Tortugas, Fla., in vast numbers nearly at the last quarter of the moon, from 

 July 1 to July 10, for breeding purposes. This species will almost certainly be 

 found to occur off the Bermudas, at about the same date. 



