528 MAZATLAN UNIVALVES 



varices, which continue over the suture, leaving deep pits, 

 and spirally ascending the spire as in Scalaria hexagona. 

 Long. 1'34, long. spir. '6, lot. *67, div. 40. 

 Hab. Acapulco, Humboldt fy Lonpland. Mazatlaji ; 1 dead 

 sp. ; L'pool Col. 



Tablet 2510 contains the specimen. 



675. MUBEX , sp. ind. 



Tablet 2511 contains one extremely young shell with sharp 

 ribs, sparsely decussated, white ; and an older one, rubbed, 

 which perhaps is not conspecific ; bearing a general resem- 

 blance to the young of M. erinaceus. 

 Sal. Mazatlan ; extremely rar, ofFSpondylus ; L'pool Col. 



676. MUEICIDEA PAUXILLUS, A. Ad. 



Murex pauxillus, A. Ad. in Proc. Zool. Soc. 1853, p. 71. 



This very small species is known from the young of its con- 

 geners by its very elongated form, and its delicate texture and 

 sculpture. Between the varices it is transparent, of a light 

 horn colour, with spiral purplish brown bands. It has 7 indis- 

 tinct varices, not continuous, sharp, crossed by a few spiral 

 ribs, of which one, generally bifid, is conspicuous on the spire. 

 The whole surface is covered with imbricated layers of growth. 

 Labrum with 5 tubercles inside ; labium smooth, not promin- 

 ent. Canal rather open, short. Nuclear whirls often solid. 

 Operculum Pisanoid, narrow, apex terminal, reddish brown, 

 transparent at the edge ; scar with a few lines of growth. 

 Epidermis extremely thin. An unusually large specimen 

 measures long. "55, long. spir. *28, lot* *29, div. 33. 

 Hob. Mazatlan ; rare ; L'pool Col. 



Tablet 2512 contains 1 sp. normal state. 2513, 3 do. elong- 

 ated, one with operculum in situ, and a separate operculum. 

 2514, 1 sp. spire depressed. 



Tablet 2515 contains 4 (out of 13) opercula which were found 

 among the fragments of Spondylus, and which have not been 

 identified with any species. They are ovate, with the nucleus 

 terminal and rounded ; very thin, orange horn-coloured ; with 

 a few ridges of growth and a large muscular scar. 



