Tethys cervina Dall and Simpson. 

 Plates. Ill- VIII, Figs. 15-35; Plates IX-X, Figs. 39-42. 



Tethys cervina Dall and Simpson, The Mollusca of Porto Rico. 

 Bulletin U. S. Fish Commission, XX, 1900, Part I. 

 (Issued Nov. 29, 1901). p. 365, PL 56, fig. 2. 



One specimen of a Tethys different from the foregoing, 

 labeled "Sand Beach, Maceio, Alagoas. July 31, 1899. A. W. 

 Greeley col." was found in the collection, no other notes ac- 

 companying it. In my opinion it is identical with the Tethys 

 cervina of Dall and Simpson taken at Mayaguez, Porto Rico, and 

 described in the publication cited above. The description of Dall 

 and Simpson is as follows: 



"Body elongated, flabby; mouth encircled by thick lips; ten- 

 tacles short; eyes inserted in front of the tentacles. Swimming 

 lobes thick, united behind at some distance in front of the hinder 

 extremity ; mantle orifice minute ; mantle ending behind in a small 

 fold; foot narrow, nearly smooth. 



"Colors: The body is a lurid gray, overlaid with reticula- 

 tions and blotches of darker color. It also has scattered, small, 

 nearly round, smoky brown spots throughout its surface. The 

 foot is smoky brown, lighter color than the spots. The inner 

 edges of the swimming lobes are beautifully and distinctly macu- 

 late, with alternating light and dark patches. The mantle is 

 colored like the body, but the dark spots are wanting, and the 

 dark reticulations are somewhat radiating. Length 7 cm. 



"Shell with a rather strong layer of lime, elliptical in out- 

 line; posterior sinus moderate. Length of shell 30; breadth 

 19 mm. 



"Mayaguez, Porto Rico." 



The following points are based upon the Brazil specimen, 

 and will serve as supplementary to the description of the former 

 authors in anatomical details. 



EXTERNAL CHARACTERS. 



Body form. The body (PI. X, fig. 41), is soft, plump and 

 smooth, the head and caudal regions being rather contracted, the 

 remainder of the body but little distorted. The total length of 

 the specimen is 40 mm., its width and height being 20 mm. 



