LECTURES ON MOLLUSCA. 185 



The large Triton Tritonis of the Pacific ocean is a great favorite with 

 the South-Sea islanders, who make a hole near the tij5, and then use 

 it as a speaking trumpet. A very similar species (T. nodiferus) in- 

 habits the Mediterranean, and has been know to crawl to the confines 

 of the British seas. One of them was kindly given by the ancients to 

 the Sea God, to make his commands better heard : and the poet sings 

 of the old Romans, 



" Buccina jam priscos cogebant ad anna duirites." 



The varices appear on every three quarters of a whirl, giving the 

 shell a somewhat distorted appearance. In the subgenus Guttemium, 

 the canal is very long and straight, as in Murex proper. It is gene- 

 rally of moderate size, and somewhat twisted. In the fusiform species 

 with a long spire, the canal is very short. Sometimes there are no 

 varices till the shell approaches maturity. There is one group (Argo- 

 bucciaum) in which the shell is thin and whelk-shaped, and the varices 

 irregular or absent. It is characteristic of the west coast of America ; 

 the A. nodosum being found in the tropics, the A. scabrum along the 

 foot of the Andes, the A. cancellatum in the extreme south, and the 

 very similar A. oregonense in the northern districts. These, with a 

 large proportion of the true Tritons, are covered with a very thick, 

 loose, and generally hairy epidermis. 



The Personce, or Mask-shells, are Tritons with a broad thin inner 

 lip, and curiously twisted mouth ; being to Triton what Malea is to 

 Dolium. The Euihrice are regarded by Dr. Gray as Tritons without 

 varix. The shell appears related to Clavella or Peristernia; but the 

 teeth of the animal have not yet been examined. 



The Banella group are very pretty shells, having a row of ornamen- 

 tal varices running up each side of the spire. In the typical species, 

 the operculum is shaped as in Murex or Pisania. But in B. crumena 

 it is formed as in Pusionella. This caused Dr. Gray to remove it to the 

 Cassis family, supposing that all the shells with round varices had the 

 usual operculum, and all those with sharp-edged ones {Ewpleurd) the 

 abnormal one. Having examined however a number of specimens of 

 the sharp-ridged Eupleura niticla, collected by Professor Adams, at 

 Panama, with the opercula in situ, I find that they belong to the 

 Buccinoid type, being oval and annular, with the nucleus near the 

 anterior end of the outer lip. This family appears sparingly, like its 

 congeners, in the Eocene strata. A curious fossil genus, Spinigera^ 

 from the Inferior Oolite, is intermediate in characters between the 

 spiny-variced Ranellas and Postellaria, and may have belonged to 

 either family. 



Family CEKiTHioPSiDiE. (False Cerites.) 



A group of very small shells were separated from the Cerites, by 

 Professor Forbes, on finding that they had a retractile proboscis, and 

 a muricoid operculum. They inhabit all seas which have been pro- 

 perly searched ; living in sheltered places near the shore among sea- 

 weeds and zoophytes. The largest of them scarcely exceeds an inch 

 in length, and one-eighth in breadth. They are all highly sculptured, 



