268 bulletin: museitm of comparative zoology. 



and widely separated, occasionally three. The collar is prominent with the 

 general dorsal oj)ening wider than in rugoso, equallinp; fully three fourths the 

 body width at that level. The dorsal lobes very low in proportion to width. 

 The ventral lobes in the t3'pe are widelj^ separated by a V-shaped opening, 

 not contiguous or overlapping as in polymorpha. The general coloration is 

 that of polymorpha, the branchiae having a similar deep wine-color with lighter 

 transverse bandings distally. Number of segments in type, near two hundred 

 and twelve. 



Length Avithout branchiae, 140 mm.; greatest width, 12 mm. 

 Locality. — Calif.: Pacific Grove (H. P. Johnson). 

 Type.— M. C. Z. 1,941. 



35. Pseudopotamilla paurops Chamberlin. 

 Pomona college journ. zool. ent., 1919, 11, p. 21. 



A single specimen, now unfortunately dry, taken at Mendocino> 

 (A. Agassiz) agrees with this species so far as the characters are evi- 

 dent. Previously known from Laguna Beach, Calif. 



36. Pseudopotamilla brevibranchiata Moore. 

 Proc. Acad. nat. sci. Philad., 1905, p. 555, pi. 37, fig. 1-7. 



Several dry specimens seem to conform to this species, though the 

 branchiae are rather longer than indicated in the original description. 

 The branchiae agree in structure and number and have the eyes 

 similar in prominence, number, and distribution over the middle 

 half of the radioles. The uncini agree very well, though in those of the 

 sixth segment the neck appears to be a httle more slender; the beak 

 and crest together have the characteristic straight anterior edge with 

 the tip of beak slightly bent forward. The specimens were taken at 

 Mendocino (A. Agassiz). 



37. Pseudopotamilla panamica, sp. nov. 



Plate 3, fig. 8. 



In the type of this form there is a total of sixty-seven somites of which nine 

 (eight setigerous) are thoracic. The branchiae are transversely banded with 

 dark, the banding dusky and not sharply limited. The branchial membrane 



