188 MAZATLAN UNIVALVES 
Orper LATERIBRANCHIATA, Clark. 
Famity DENTALIAD #. 
Genus DENTALIUM, Linn. 
The fullest account of the animal of this remarkable tribe, 
will be found in Clark, Moll. Test. Mar. Brit. pp. 225—238. 
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 LIRATUM, 2. s. 
D.t. solidé, alba, tereti, livis longitudinalibus tenuissimis 
ereberrime induté ; liris in juniorem circiter xii., in adultam 
circiter Xxx., acutis, haud equalibus ; parum arcuata, apertura 
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, lat. *011—'03. 
Hab.—Mazatlan ; off Modiola capax, Chame and Spondyli, 
very rare; L’pool 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. Mal. 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- 
eribed 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. 
Hab.—Mazatlan ; 1 sp. off Spondylus calcifer ; ZL’pool Col. 
