PTERONOTUS. 87 



Described by A. Adams under the name of alabastrum which 

 is preoccupied by ReeA'e. Very like M. triqueter, Born, but 

 differs in having only a single intervariceal rib. 



M. MACROPTERUS, Desh. PI. 40. fig. 517. 



Of the same general appearance and color as the three pre- 

 ceding species, and appearing like a particularly well-developed 

 M. hnyua. The four-lobed, widely expanded, scabrous foliation 

 of the marginal varix is its chief characteristic. Length, 1*5 



inches. 



Rob. unknown. 



In the original figure the opercurnm approaches purpuroid, but 

 the nucleus is scarcely marginal. It has evidently been care- 

 lessly figured. Reeve's figure has the typical operculum of 

 Murex. 



M. TRIPTERLS, Born. PL 41, fig. 531. 



Columella and lip dentate, foliations very wide, oblique, regular. 

 Light yellowish-brown, darker within the aperture. 



Length, 2 inches. 



Red Sea, Ind. 0., Philippines (Upolu). 



M. PTNNATUS. Wood. PL 41, tigs. 526, 530. 



This well-known Chinese species attains a length of 2'5 to 3'5 

 inches. It is always pure white throughout. M. pelluciduz, 

 Reeve (fig. 530), " found upon a coral bottom at a depth of 7 

 fathoms, Island of Bantayan, Philippines.' 1 is evidently the same ; 

 in fact, I have before me a suite of specimens connecting the 

 two forms. 



M. CLAVUS, Kiener. PL 41, figs. 533, 534. 



Whitish or flesh-colored. Length, 3*25 inches. In the young 

 shell (= M. bipinnatus, Reeve, fig. 534) the nodes and revolving 



stria? are much more prominent. 



Philippines. 



& 

 * * 



M. OSSEUS, Reeve. , PL 41, figs. 525, 527. 



Whitish, more or less tinged with brown. Length, 2*75 inches. 



Hab. unknown. 



This is the first of a group of species in which the foliated 

 varices terminate on the shoulder of each whorl in a hooked 



