260 PROCEEDINGS OF THE ACADEMY OF [Aprii, 



part is a short, somewhat depressed, rapidly tapered cone obscurely 

 divided into about eight rings and bearing at the apex two pairs of 

 small but distinct, slender, divergent tentacles. 



The parapodia agree with Johnson's figures; anteriorly they are 

 small, but gradually increase in length until the posterior ones become 

 quite prominent and slender. 



ARICIID^. 



Aricia johnsoni sp. nov. (Plate VIII, figs. 30-33). 



The solitary specimen upon which the following description is 

 based lacks perhaps about 100 caudal segments, the remaining 182 

 segments measuring 72 mm., and in the widest part of the anterior 

 region is 3 mm. wide and 1.8 mm. deep. 



Prostomium small, acutely conical, about twice as long as the basal 

 width, bearing at the apex a minute cirriform palpode, the base slightly 

 swollen and on the dorsal surface exhibiting an obscure transverse 

 row of minute specks, probably eye-spots. 



Peristomium a truncated cone nearly as long as the peristomium 

 and two to two and one-half times as broad ; on its venter is a quadrate, 

 cushion-like area, behind which the minute mouth lies between it and 

 somite II. 



Anterior region of body strongly depressed, elliptical in section and 

 scarcely two-thirds as deep as wide, increasing in width rapidly to X, 

 then more gradually to the widest point at XVIII or XIX, following 

 which is a rather marked constriction extending over about ten seg- 

 ments (those bearing the pectinated ventral folds). The entire pos- 

 terior region is very strongly convex below, flattened above, and bears 

 the parapodial lobes, setae and gills in a dense brush-like arrangement. 

 Intersegmental furrows well marked ; segments of anterior region one- 

 third to one-fifth as long as broad, obscurely biannulate owing to a 

 slight welt and groove encircling them opposite the parapodia; seg- 

 ments following region of ventral pectinations simple and much shorter. 

 Pygidium unknown. 



The ventral half of the welts alluded to above is better developed 

 than the dorsal half and bears the pectinated folds which are incipient, 

 as two or three small slender papillae, on each side of the neural line 

 of XXI and XXII. On XXIII they reach from the neuropodium to 

 the middle line, consisting of five or six closely contiguous smaller 

 papillae at the dorsal end and two or three larger detached papilla? at 

 the ventral end. On succeeding somites the number of papillae in- 

 creases to fifteen or sixteen on each side, all but the two or three ven- 



