188 MAZATLAN UNIVALVES 



OBDEB LATEBIBBANCHIATA, Clark. 



FAMILY DENTALIAD.E. 

 GENUS DENTALIUM, Linn. 



The fullest account of the animal of this remarkable tribe, 

 will be found in Clark, Moll. Test. Mar. Brit. pp. 225238. 

 It has only a faint analogy with Fissurella ; and differs so 

 much from even the most aberrant of the Scutibranchs that 

 the Order, proposed by Clark, is adopted. There are many 

 points of analogy with the Lamellibranchiate Mollusca, and 

 some with the Annelids. Individuals appear to be very rare 

 at Mazatlan, perhaps in consequence of the scarcity of For- 

 aminifera, on which these blind, almost headless creatures 

 voraciously feed. 



244. DENTALIUM LIBATUM, n. s. 



D. t. solidd, alba, tereti, liris longitudinalibus tenuissimis 

 creberrime indutd ; liris in junior em circiter xii., in adultam 

 circiter xxx., acutis, baud cequalibus ; parum arcuatd, aperturd 

 branchiali simplici. 



One perfect, though rather small, specimen was found en- 

 tangled in the byssus of Modiola capax ; fragments occurred 

 of a much larger size. Long. '25, lot. 'Oil '03. 

 Hab. Mazatlan ; off Modiola capax, Chamse and Spondyli, 

 . very rare ; Lpool Col. 



Tablet 879 contains the perfect specimen, a small do. wedged 

 in the mouth of Trivia sanguinea, and a fragment of a large 

 one, '065 across. 



245. DENTALIUM HYALINUM, Phil. 



Zeit.f. Mai. 1846, p. 55, no. 27. 



Tablet 880 contains a minute shell of a hyaline texture, with 

 an opaque line running along the inner curve, which may be 

 accidental. It probably belongs to the above species des- 

 cribed by Philippi from Mazatlan, although that is said to be 

 "versus apicem tenuissime striata, " while this, which is ex- 

 tremely young, is smooth. Long. '07, lat. '01 '025. 

 Hob. Mazatlan ; 1 sp. off Spondylus calcifer ; L'pool Col. 



