346 DR. p. p. CARPENTER ON THE SHELLS OF PANAMA. [June 23, 



126. Triton chemnitzii=Argobuccinum nodosum, M, 580. These 

 shells are small and turreted. Those Prof. Adams marked " T. cin- 

 ffulatiim. Lam., E. Indies," are much more like the Mazatlan shells. 



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

 group from the Pacific Coast, from the Gulf of Mexico, and from 

 the China Seas are very difficult to discriminate. 



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

 scarcely he called a Triton, even of the Epidromus type. It may 

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

 anterior sinus, near the canal, like Jtostellaria. 



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



136. Murex dubius=Muricidea duhia, M. 673. 



137. Murex erosus^^Muricidea e. 



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

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

 nigritus than the heavy stumpy shells usually seen. His young 

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

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

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

 out locality) belong to the typical nigritus. Phyllonotus radix and 

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

 into ambiguus : v. M. 666. 



139. Murex rectirostris. This and kindred species run into each 

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

 young a specimen in bad condition. 



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

 fect to affiliate: v. M. 665. 



141. Murex regius=PhgUonotics 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 tropical 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 MoUusca, pp. 39, 42) leaves the round-variced Ranellids, 

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

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

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

 ternal." The operculum of R. ccelata, 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 (Ecinebro:; nucleus near the 

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

 in Purpurids, with about three roughly angular ridges of growth. 



