THE NAUTILUS. 113 



posterior short and rounded; interior smooth, the muscular 

 scars prominent, the anterior more rounded than the other; basal 

 margin with ten or twelve crenulations in the adult, more in 

 the young; lateral margins smooth. Height of adult 38; 

 breadth 35; diameter 18 mm. 



Shell heap near Montevideo, Uruguaj 7 '. U. S. N. Museum, 

 No. 215083. Coll. Felippone No. 556. 



Though the valves received are not fresh, they show the color 

 markings. The most characteristic features of the species are 

 the narrow umbonal angle (100) and unusually inequilateral 

 umbonal area, recalling the conditions in some species of 

 lAmopsis. 



CALLOCAKDIA (AGRIODESMA) FELIPPONEI n. sp. 



Shell most closely resembling C. morrhuana Linsley (+ C. 

 convexa Say) of the New England coast, and best described by 

 a differential diagnosis from that well-known species. Surface 

 of the present species similar in color, texture, and concentric 

 sculpture; form more triangular, the umbones smaller, the 

 anterior dorsal slope more depressed, the lunule somewhat 

 longer; the posterior slope longer and less roundly arcuated into 

 the less arcuated basal margin; the ligament markedly shorter, 

 the hinge teeth larger and heavier; the pallial sinus similar in 

 form and length but somewhat wider; the beaks appear more 

 prominent, and the posterior cardinal tooth in both valves is 

 relatively much larger and stronger. 



Height of t} 7 pical specimen 40 ; length 50 ; diameter 27 mm. 



Maldonado, Uruguay ; U. S. N. Mus. No. 215082. Coll. 

 Felippone, No. 582. 



Young specimens of this species were collected by the U. S. 

 Fish Commission Steamer Albatross in 59 fathoms, mud, off 

 Rio de Janeiro ; the bottom temperature 57 F. These were 

 referred to C. aresta Dall, of my Porto Rico report, not being 

 old enough to display the differential characters. There is a 

 thin, dirty grey, dehiscent periostracum on the present species. 



The species is named in honor of Dr. Florentine Felippone of 

 Montevideo, who has devoted much time to the study of the 

 Natural History of Uruguay. 



