^OLis. 241 



mon-colored, a hundred or more arranged on each side hi close-set, 

 regularly spaced series, somewhat flattened and apparently perfo- 

 rate at tip. Foot hroad, the anterior angles prolonged into tenta- 

 cular appendages, the tail narrowing rather suddenly to an acute 

 point. Length, one and three fourths inches ; breadth, four fifths 

 of an inch. 



In Cliarles River, near Craigie's Bridge. 



It is a true ^Eolis, of large size, its form much the same as that 

 of jE. papulosa, differing from it chiefly in its sharper and serrated 

 tentacles, and in the color of the branchiae. From jE. Mananensis 

 it differs not so much in color as in its more flattened body, more 

 numerous and less clustered branchice. 



Section 2. — Flabellina. Body slender ; dorsal tentacles lam- 

 inated ; oral tentacles long. Branchiae linear, clustered ; angles of 

 the foot much produced. Spawn of many undulated coils. Lin- 

 gual plate with a strong central spine and marginal denticles, and 

 two separate plain lateral spines. 



.fflolis Bostoniensis. 



Pl.vte XIX. Figs. 266, 273, 274, 27.5, 283. 



Body elongated, lanceolate, delicate drab-color, Avith a silvery line on the tail 

 and on the back of the anterior tentacles, which are long, subulate; posterior 

 tentacles shorter, serrated at tips ; branchiie curved lanceolate, nucleus drab-col- 

 ored, tips white, in four to six distant groups on each side ; angles of foot much 

 produced. 



Eolis Bostoniensis, CouTHOUT, Journ. Bost. See. Nat. Hist. ii. 67, pi. 1, fig. 1. — Gould, 



Inv. 6. 

 ^'EoUs Bostoniensis, Stimpson, Check Lists, 4 (1860). 

 Eolidia Bostoniensis, Da Kay, N. Y. Moll. 9, pi. 5, fig. 96 (1843). 



Body regularly attenuated, rounded above, of a bluish or roseate 

 tint, having a bright silvery line on the carina of the tail ; the pos- 

 terior face of the anterior tentacles is also often silvery. Branchiae 

 scymitar-shaped, nucleus drab or slightly russet, tips conical, silvery- 

 white ; they are arranged in five or more distant groups on each 

 side, the anterior range having sixteen filaments arranged in cubic 

 quincunx, the dorsal ones being longest, and in the succeeding 

 groups they are fewer and shorter ; these tufts curve backwards and 

 inwards, forming arches over the back. Tentacles about equal in 

 16 



