1880.] NATURAL SCIENCES OF PHILADELPHIA. 117 



This species ma}' perhaps be the Triopa Garpenteri of Stearns ; 

 it has, like that, five branchial leaves, and does not differ much in 

 the number of the dorsal appendices (six) or the form of the 

 frontal margin ; but the dorsal nodosities of the last species are 

 orange-colored, and the rhinophoria, the dorsal appendices, and 

 the branchial leaves tipped with orange. Through the great 

 kindness of Mr. Dall I have seen a drawing of the animal of 

 Stearns, from specimens secured after those he had described, 

 but they do not give more details than the original description ; 

 and Stearns seems not to possess the original specimens, which 

 very likely are lost forever. On the other side, it must be remem- 

 bered that Sars (Beretn. om en i Sommeren, 1849, forctagen 

 zoolog. Reise i Lofoten og Finmarken, 1851, p. T4) found "the 

 young individuals of Triopa lacera (M.) entirely white, also on 

 the tentacles and gills, merely the liver shines brownish through 

 the skin." 



EXPLANATION OF THE PLATES. 



An asterisk denotes that the drawing is by camera lucida, the 

 fraction denotes the magnification. 



The serial numbers of the plates (Part I, plates i-viii, Part II, 

 plates ix-xvi) are solel}- referred to throughout the text. As 

 Part II appears in another volume of the Proceedings of the 

 Academy, the plates of Part II have been for that reason renum- 

 bered with a second set of numbers, Plate ix being Plate i, Plate x 

 being Plate ii, etc., in the new volume. The serial numbers re- 

 ferred to in the text, follow the new numbers for Part II in 

 parentheses throughout this explanation. 



Plate I (IX). 



Jorunna Johnstoni (A. and H.), 



1. a, stalk of the (6) gangl. genitale; c, gangl. genit. secunda- 



rium,* ^^. 



2. Granules of the back, stiffened by spicula,* ^f^. 



3. Part of the middle of the radula, with the two innermost 



lateral plates ; a, rhachis,* ^f ^. 

 i. The hook of a plate from the back,* ^s., 



