1880.] NATURAL SCIENCES OF PHILADELPHIA. 103 



plates, farther backwards eighteen developed and three younger rows, 

 the total number thirty; the plates denticulated as previously men- 

 tioned, the height of the large plates rising to 0,7 mm. ; the number 

 of external plates four to five. The oesophageal diverticle of a largest 

 diameter of about 3.0 mm. The pars pylorica of the intestine of about 

 4.5 mm. length, with higher folds than in the rest of the intestine, which 

 had a length of about 15.0 mm. ; the bag at the first part of the intes- 

 tine 1.5 mm. long. The liver 12.0 mm. long by a breadth of 8.0 and a 

 height of 6.0 mm. The sanguineous glands whitish, 5.0 mm. long by 

 a breadth of 6.0 mm. and 2.0 mm. thick, convexo-concave, the fore-end 

 flattened (by the buccal crop), the hinder end with two transverse fur- 

 rows (produced by two coils of the spermatoduct ; the anterior genital 

 mass 8.0 mm. long by a breadth of 3.5 and a height of 7.5 mm. The 

 ampulla of the hermaphroditic duct 5.0 mm. long, whitish. The coils 

 of the spermatoduct and of the vagina in this individual covering the 

 upper side of the mucous gland, and ascending to the back between 

 the pharyngeal bulbus and the liver ; a coil of the former embraced 

 the sheath of the radula. The first part of the spermatoduct 12.0 mm. 

 long, the last of the length of about 25.0 mm ; the penis about 3.5 mm. 

 long, the armature as usual. The spermatotheca nearly spherical, of 

 3.5 mm. diameter ; the spermatocysta yellowish, round, with a diameter 

 of 1.5 mm. ; the chief duct (vagina) 33.0 mm. long with a general 

 diameter of 1.2 mm. ; the structure of the wall as above ; the last, nar- 

 rower part (from the m. retractor downwards), 5.0 mm. long. 'J he 

 vestibulum, as well as the inferior part of the vagina and of the penis, 

 with very scanty black pigment. 



4. Acanthodoris caerulescens, Bgh., n. sp. Plate XIII, fig. 6-7 ; Plato XIV, fig. 16. 



Color paginas superioris corporis caerulescens. 



Dentes radulae hamo per totam fere longitudinem deuticulato. 



Hah. Mare Beringianum (Nunivak Island). 



One specimen of this species was found by Dall at the north end of 

 Nunivak Island, Bering Sea, in July, 1874, on stony bottom, at the, 

 depth of eight fathoms. 



According to Dall, the color of the living animal was bluish. The 

 animal preserved in alcohol had the length of 14.0 mm. by a height of 

 5.0 and a breadth of 8.0 mm. ; the length of the foot was 12.5 mm. by 

 a breadth of 6.5 mm. ; the height of the rhinophoria 2.0, of the bran- 

 chial leaves 1.5 ram. The color uniformly yellowish-white, with the 

 back of a slightly bluiah hue. 



