= rom: dsitialio. ae 159 
43. Modiolopsis prerupia.—Elongate (lett about twice the great- 
est height), enlarging somewhat posteriorly, dorsal margin straight or 
very slightly arcuate, ay into the posterior margin; inferior ex- 
cavaie anterior to m ; front abruptly truncate ; latera! surface ex- 
cavate from the beak ponenseely downward, also an oblique depression 
adjoining anterior muscular impression ; a few faint rays from the beak 
over the posterior surface, concentric strie of growth distinct; anterior 
pest impression smaspinals arenvaley ge small and su uborbicular, 
Length 1,4, ine greatest height 353, L; apical angle 100°. 
Near ML. faba of Hall. —llawarra. 
44. Modiolopsis imbricata. —Moderately elongate, enlarging poste- 
riorly, very sdtaclapaels dorsal margin straight, and prolonged ; infe- 
rior margin straight anteriorly, front rounded ; lateral surface depressed 
or somewhat excavate from the beak obliquely backward and down- 
ward, having neat concentric subimbricate markings (and some fine 
. Mo dio ue arcodes.—A thick species aes the the scroll 
in form aed in exterdal — ngs ; but it is much broader in pimporsvn, 
than shell, being much ey nged posteriorly than in M imbricata ; 
line from beak pos ight soni decidedly carinate, beaks thicker. 
The fibrous texture is very distinct The anterior muscu 
in the Myophora of Bronn.—Length 12 inch; height much less than 
half length. Looks much like an Area in general fo orm.- oe 
Hill. 
46. Modiolopsis acutifrons—Thick, elongate, very much broa 
posteriorly ; cardinal line straight, very oblique, very much shorter than 
shell; front acuminate, posterior broadly rounded ;_ eaotasine margin ex- 
cavate near anterior extremity and also just posterior to beak ; lateral 
surface den 2 a downward and backward ascaiets: “ous beak to 0 pos- 
erior margin very convex, hardly carinate ; surface marked with a few 
concentric folds, and some lines of growth. Anterior muscular impres- 
* Judging from this texture, the species of Modiolopsis (Hall) are more allied to 
Sitio than ‘ola aut although having a large and strong anterior muscular im- 
press 
