P DR. P. P. CARPENTER ON THE SHELLS OF PANAMA. 



126. Triton chpmnif:il= Arijchucc't/nun nodostim, M. 580. These 

 jliell?; are small ami turreted. Those Prof. Adams marked *' 2'. cin- 

 (/u/atian, ha.m., E. Indies," are much more like the Mazatlan shells. 



127. Triton constrictus=^Distortio c. The specimens of this 

 group from the Pacific Coast, from tlie Gulf of i\le.\ico, and ironi 

 the China Seas are very difficult to discriminate. 



128. Triton fusoides. This unique and very elegant shell can 

 scarcely be called a Triton, even of the Epulromus type. It may 

 perhaps rank with Euthria, but is peculiar in possessing a distinct 

 anterior sinus, near the canal, like Rostellaria. 



129. 130, 131, 132*, 133, 134*, 135. Stent. 



f 

 rj6. Murex duhiiis=^Muricidea dxihia, M. 673. 



137. Murex erosus=Muricidea e. 



138. Murex radix = Phyl1onotus r. The Professor's specimens 

 of this species are remarkably fine, more nearly resembling the Gulf 

 miyritus than the heavy stumpy shells usually seen. His youu^ 

 specimens are heavier, but more turreted, than the young nicjritus. 

 The opercula appear to have fewer frills ; but such differences may 

 be due only to station. The specimens he marked ambiyuus (with- 

 out locality) belong to the typical niyritus. P/ii//lonofus radix and 

 viyritas graduate into each other almost as freely as the latter does 

 iuto ambiyuus: v. M. 666. 



13t. Murex rectirostris. This and kindred species run into each 

 other too closely, when adult, to speak with any confidence ou so 

 young a specimen in bad condition. 



140. Murex recurvirostris. This specimen is also far too imper- 

 fect to affiliate: v. M, 665. 



}4l. Murex reyius^=PhyUonotus r., M. 670. 



142. Murex salebrosus= Vitularia s., M. 612. The curious group 

 of Muricoid Purpurids culminates on the West American shores. It 

 is represented in the north temperate regions by Cerastoma, on the 

 warmer shores by Chorus, and in the trojiical regions by Vitularia. 

 The Lower Californian Murex belcheri, Hds., belongs to the group. 

 Dr. Alcock (who has succeeded the late Capt. Brown as Curator of 

 the Manchester Natural History Museum) has pointed out very well- 

 marked physiological distinctions between the two families, which 

 are coordinate with the differences in the opercula. 



* Dr. Gray (Guide to Mollusca, pp. 39, 42) leaves the round-variced Ranellids, 

 as Apollon, in the Tritonidce, " operc. annular, nucleus subapical, within the 

 apex ;" but removes the sharp-variced species, as Ranella, to the Cassidida, and 

 figures the opercuUnu like Bezoardica, "half-ovate, nucleus central, lateral, in- 

 ternal." The operculum of R. aclata, No. 132, is almost identical with Murex, 

 and the shell accords with Apollon; but R. nifida. No. 134, which has very sharp 

 varices, has its operculum widely removed from Bezoardica. It is closely related 

 to that of Cerastoma, Rhizocheilus, and some of the Ocinebrw; nucleus near the 

 anterior end of the labrum ; lahral portions of the annular layers eroded ; scar as 

 iu I'tirpunds, With about th;ee roughly angular ridges of growth. 



182 



