12 MUKEX. 



aperture and other characters show that the species is related 

 to M. ramosus. The short development of the frond and 

 the exfoliation of the varix at the margin of the aperture 

 give it a different aspect. 



51. angdliferds, f. 66, 68. — Testa pyriformis ventricosa, 

 subtrigona, fusca, vel alba fusco fasciata, spiraliter lirata, 

 inter varices tuberculo magno vel duobus armata ; frondibus 

 spiniformibus brevibus, infra ad marginem aperturae angu- 

 latim exfoliatis ; canali producto ; spira brevi, anfractibus 

 angulatis, ultimo inflato, ad suturam crenatis, margine aper- 

 tures unidentato. — Like a small M. ramosus with its spires 

 reduced. In regard to the tooth and the exfoliated fronds 

 beneath it, the shell much resembles M. cyacantha, in which 

 they are, however, much more developed. 



52. pondeeosus, f. 67, Chemnitz. —Testa brevi, quadrangu- 

 lata, crassissima, pallide fulva, spiraliter impresso-lirata, 

 varicibus latis, crassissimis, fere nudis, ad angulum obtuse 

 unispinosus : ad canalem breviter bispinosis ; canali brevi, 

 apertura magna, margine externo crenato, infra unidentato. 

 — Believed by some conchologists to be a thickened dwarf 

 variety of M. angularis. 



53. elongatus, f. 70, Lamarck. — Testa fusiformis, M. 

 ramosi similis, sed elongata, haud trigona, spira elevata, 

 anfractibus productis, angulatis. — If one could soften the 

 substance of a small M. ramosus, and pull it out at the spiral 

 end, drawing the body where narrower, the product would be 

 exactly what we find in M. elongatus. It is with the former 

 that Lamarck compares it, and most points in the descrip- 

 tion accurately correspond, which is not the case with the 

 shell ascribed to the species by Mr. Reeve. 



54. caecitrapa, f. 64, 65, Lamarck. — Testa scabra, alba, 

 conspicue fusco-fasciata ; spiraliter distanter angulatim lirata, 

 interstriata, inter varices plerumque tuberculoso-uniplicata ; 

 varicibus crassis, pone foveolatis, frondibus breviusculis, den- 

 tato-laqueatis, recti usculis, ad aperturam quaternis et duabus 

 intermediis, ad canalem duabus ; spira breviuscula, anfracti- 

 bus angulatis, ad suturam crenatis ; apertura magna, margine 

 denticulate et angulatim crenato. — The most characteristic 

 variety is the one with rather short fronds, and the broad 

 bands showing sharply on a white ground. The caltrop is an 

 ancient instrument of war, thrown on the ground before an 

 enemy to entangle and injure his horse's feet. 



