EMBLETONIA. 251 



Genus E.IIBLETOXIA, Aldeu and Hancock. 1851. 



Tentacles two, linear, dorsal ; the oral pair flattened into two 

 lateral lobe.s, Branehias few, fusiform, set generally in single se- 

 ries down the sides of the back. Tongue a single plate bearing a 

 central spine and lateral denticles. Jaws corneous. 



Embletonia fuscata. 



Plate XVI. Figs. 229-232. 



Animnl sulvcylimlrical, narrowing backwards ; tail short, pointed ; drab-col- 

 ored ; head largx'r than body, liroad, angles ronnded, slightly emarginate ; tenta- 

 cles short ; Ijranchite club-slia[)ed, arranged in five or six tufts on each side of 

 the posterior portion of the body ; angles of foot not dilated. 



Animal minute, sub-cylindrical, narrowing backwards, tail short 

 and pointed. Color varying from pale drab with a few dusky points 

 to a smutty slate-color, made so by being completely covered by the 

 dusky points ; sometimes only the edges of the foot are dusky, and 

 again there are blotches made up of aggregated dots, and on the 

 whole the color may be called dusky. Head large, somewhat 

 broader than the body, angles rounded, convex in front, or slightly 

 emarginate. Tentacles short, linear, dotted, capalde t)f corrugation. 

 Branchial papillae clul)-shaped, arcuate, dusky, tii)i»ed with light gray, 

 arranged in five or six tufts on each side, the two or three anterior 

 tufts containing three, and the others two papillas of very unequal 

 size ; the first tuft is quite remote from the head. Foot slate-col- 

 ored, as wide as the body, angles not dilated. Length, three twen- 

 tieths of an inch ; l)i'eadth, one fortieth of an incli. 



Found in Charles River on logs in timber docks, and at South 

 Boston Bridge, on Laomcdca g^eniculata, July, 1842 and 1865 ; in 

 Charles River, October QSfimj)SO)i,^. 



This curious genus has been recognized but a short time, and 

 was hrst set apart (1844) liy Alder and Hancock, under the name 

 of PtcrocJiilus ; but as this name had l)een applied to a genus of in- 

 sects, they substituted the name Embletonia. The species are all 

 quite minute, and only three have been liitherto noticed, all of which 

 seem quite different from those observed here. But as tlie sjiecies 

 are evidently subject to wide variation in color, size, and numl)er of 

 branchiae, the identity or number of species must be yet uncertain. 

 This spccie.j was found in great numbers on the long, floating tufts 



