106 AMERICAN MARINE CONCHOLOGY. 



The ova are deposited in the latter part of August. They are 

 minute, white, and enveloped in a gelatinous mass, which is glo- 

 bular, hj-aline, and somewhat larger than the animal. 



Massachusetts $ 



2. P. QUADRATA, Searles-Wood. Pig. 218. 



Mag. Nat. Hist. n. ser., ill. 461, t. 7, f. 1. 1839. 

 PMline formosa, Stimpson, Bost. Proc, iii. 334. 1850. 



Shell minute, squarely globose, subtruncated anteriorly, white, 

 shining, subopaque, thickened posteriorly, punctured with inequi- 

 distant, sometimes undulated, revolving striae ; apex deeply exca- 

 vated, columella sinuose, broadly and lightly callous ; lip creuu- 

 lated posteriorly ; aperture very wide. 

 Length 4.5, diam. 3.5 mill. 



New England, northwards. {Zetlands.') 



3. P. LiNEOLATA, Couthouy. Fig. 219. 



(Bulla.) Bost. Journ. Nat. Hist., iii. 179, t. 3, f. 15. 1832. 



Shell very small, oblong-ovate, broadest at the base, thin and 

 fragile ; whorls three ; the last inflated and enveloping all the 

 others, with numei'ous impressed minute revolving striae ; spire 

 small, prominent, flattened, with the outer lip arising from near 

 its summit ; aperture the whole length of the shell, narrow above, 

 dilated beneath, somewhat effuse at the base ; a faint oblique fold 

 near the middle of the columella ; pale-brown, with a thin ferru- 

 ginous epidermis ; within glossy yellowish-white. 



Length 3.75 mill., diam. 2 mill. 



Massachusetts, northwards. 

 According to Mr. Gwyn Jeflfrejs this species ^= lima., Brown, 

 1827. 



Section B. NuDiBRANCniATA. 



Gills exposed or contractile into cavities on the surface of the 

 mantle ; adult animal without any shell ; larva shell-bearing ; foot 

 elongate, formed for walking ; sexes united. 



* Gills plumose, on the hinder part of the mantle, disposed in a circle or 

 semicircle, round the vent. Anthohranchiata. 



Family Doridid^. Mantle-edge simple ; gills surrounding the 

 vent, on the middle of the hinder part of the back, in a common 

 cavity. 



The gills are retractile into a common cavit}'', and the mantle is 

 very large, either entirely or almost covering and concealing the 

 foot. 



