300 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



PI. 2, fig. 19. 



■ This small, widely distributed species may be recognized by its 

 firm, slender, cylindrical body, usually only 8-15 mm. in length, 

 somewhat narrower towards both extremities ; flesh color or pale 

 yellowish, mottled on dorsal surface with brownish blotches and 

 dots of various shades and with considerable variation in distribu- 

 tion, often being mainly collected into a series of transverse bands 

 with a few scattered blotches between (PI. 2, fig. 19). 



The head is continuous with body and provided with 4 ocelli. 

 Proboscis armature as in other species of Tetkastemma. 



Habitat. — On piles of wharves, and on rocks, among algae, bryo- 

 zoans, ascidians and other growths. Widely distributed in Northern 

 Hemisphere, occurring on the northern coasts of Europe, in the 

 Mediterranean, and on both the east and west coasts of North 

 America. Monterey Bay, California, in 20 fms. (J. F. Abbott). 



83. Tetrastemma (Oerstedia) reticulatum Coe. 



Harriman Alaska Expedition, 11, p. 170, PI. 14, figs. 7, 8; PI. 20, 



figs. 7-9, 1904. 



PI. 2, figs. 16, 17 ; Text-figs. 61, 62. 



This is a minute species, measuring but 8-15 mm. in length when 

 sexually mature, and less than 0.5 mm. in diameter, much resembling 

 typical species of Oerstedia in form and movement, as well as in 

 firmness of body and in general appearance. The peculiarities of the 

 species of this genus do not seem to be sufticiently pronounced, how- 

 ever, to warrant their separation from the genus Tetrastemma. 



Bod}^ short, thick, rounded ; head usually somewhat narrower 

 than body, with a pair of oblique lateral grooves situated opposite 

 posterior pair of ocelli. 



Color. — Ground color of body white, with rectangular and lon- 

 gitudinal brown markings which obscure most of the white color of 

 dorsal surface (Pi. 2, figs. 16, 17). Two varieties, presenting widely 

 different arrangement of markings, w^ere met with, and these in 

 extreme cases would suggest two different species. Color of mark- 

 ings varies from light brown to chocolate or reddish brown. Head 



