610 PROCEEDINGS OF THE AMERICAN ACADEMY. 



posteriorly until it merges into the long, pointed tail, which is much 

 narrower and thinner than the body, and nearly one third the total 

 length of the animal. The head is blunt and squarish. The ten- 

 tacles are cylindrical, non-retractile, and one fourth the length of the 

 rhinophores. 



" The rhinophores are non -retractile, cylindrical, each having from 

 three to six cup-like, equidistant folds on the posterior surface of its 

 distal two-thirds. 



" On the sides and dorsum of the body there are a number of short, 

 clavate papillae, the tips of which are translucent. The number is not 

 constant, but ranges from 16 to 19. Their distribution is as follows : 

 — Of eight which are constant in position, two occupy the median 

 plane, one of them behind the rhinophores about one sixth of the dis- 

 tance between base of branchial plumes and rhinophores, the other in 

 front of the plumes about one fourth of the same distance. The re- 

 maining six are arranged in pairs near the median plane, one pair a 

 little in front of the rhinophores and distant from each other about the 

 thickness of a papilla ; a second pair slightly in front of the posterior 

 median papilla and a little further apartthau the an terior pair; the 

 third pair nearly as much behind the plumes as the posterior median 

 papilla is in front of them ; these are still further from each other. 



" In addition to these eight papillae, there are on the dorsum near its 

 lateral margins from eight to eleven papillae. There are four on each 

 side, or four on one side and five on the other, or, finally, five on one 

 side and six on the other. 



" The ground color is whitish, mottled with light brown arranged in 

 irregular splotches. A less abundant darker brown is disposed in 

 streaks across the lighter brown. The foot is white and without any 

 color markings. Its margin, as well as the tips of the papillae, is 

 translucent. 



" The foot is smooth and slightly notched anteriorly. The mouth is 

 T-shaped [or a vertical slit]. The anal opening is subcentral in posi- 

 tion, and the excretory orifice is just posterior to it, both being sur- 

 rounded by the gills. 



" The gills consist of four or five more or less irregularly branching 

 plumes. 



"When at rest, the body is shortened, the tentacles drop back 

 alongside the body, and the rhinophores lie on the dorsum. The 

 papillae, which are constantly in motion when the animal is crawling, 

 are bent dorsally when it is at rest, and are often knobbed. Under a 

 low power lens one can see the long cilia in motion. The animal 

 assumes a variety of positions while in this resting state, and it fi-e- 



