SPIRAXIS. 17 



Shell similar to Spiraxis s. sir., but regularly tapering, - 

 evenly, finely 'ribbed, with no parietal lamella. Type S. 

 costulosus. 



Euspiraxis was instituted without definition by Pfeiffer in 

 1855 for what he intended as the typical group of Spiraxis, 

 comprising the following species: acus Shuttlw., costulosa 

 Ad., inusitata Ad., brevis Ad,, aberrans Pfr., consimilis Rve., 

 and ? paludinoides Orb. In 1860 von Martens selected Sp. 

 costulosus Ad. as the type. Although Pfeiffer'si intention was 

 clearly to coin a new name for the typical Spiraxes, as is 

 shown by his inclusion of all of Adams' species in his list, yet 

 since von Martens selected costulosa as the type, it seems al- 

 lowable to restrict Pfeiffer's group to species of the costulosa 

 group. If we take the first species of Pfeiffer's list as type 

 of Euspiraxis, the name will replace Volutaxis of Strebel. 



Euspiraxis was enlarged from time to time by the 'addition 

 of species from the Antilles, the Oriental region and other 

 places until it became -a heterogeneous assemblage of forms 

 belonging to two or three families -and many genera. It is 

 now restricted to two small Jamaican species, closely related 

 to typical Spiraxis. 



3. S. COSTULOSUS C. B. Adams. PL 1, figs. 4, 5. 



' ' Shell elongate-conic ; whitish or horn colored ; with thirty- 

 five or forty obtuse approximate transverse ribs : apex obtuse ; 

 spire with the outlines almost rectilinear except near the 

 apex; whorls seven and one-half, very convex, with a deep 

 suture; last two or three whorls with a spiral constriction on 

 the middle, which gradually increases to the labrum, which 

 is much indented by it; columellar lamina large. Mean di- 

 vergence about 13; length .175 inch; breadth .04 inch." 

 (Adams). 



Jamaica : 



Spiraxis costulosa C. B. AD., Contrib. to Conch, no. 6, p. 

 88 (March, 1850). PFR., Monogr. iii, p. 470. 



In perfect adult individuals there is a callous tooth within 

 the outer lip, and the peripheral constriction is marked in- 

 side by more or less callous deposits, such as the related species 



