HANLEYA. 17 



Leptochiton (Deshayesiella) curvatus Cpr., DALL, Proc. U. S. 

 Nat. Mus., 1878, p. 314 (name and generic characters only). 

 Deshayesiella curvata Cpr. MS. p. 10. 



This shell externally looks very much like an Acanthochiton 

 without the pore bunches, of which there is no trace. The planed 

 off parts inside the apices are unusually large. (Cpr.} 



Genus II. HANLEYA Gray, 1857. 



Hanleya GRAY, Guide Syst. Dist. Moll. B. M., p. 186, type " H. 

 debilis Gray= Chiton hanleyi Thorpe." Hanleyia DALL, and Han- 

 leia of CARPENTER, MS. 



Anterior valve having an insertion plate without slits, but rough- 

 ened ; intermediate and posterior valves having no insertion plates; 

 eaves small; girdle with fine spines ; no girdle pores. 



This genus differs from Leptochiton and Deshayesiella in possess- 

 ing an insertion plate upon the anterior valve. It differs from 

 Hemiarthrum and Microplax in having no insertion plates upon the 

 intermediate and posterior valves, and in lacking girdle pores. 



In Dr. Gray's original generic diagnosis, the girdle is said to 

 have pores furnished with tufts of bristles. This has proved to be 

 an error, the statement evidently having been based upon a speci- 

 men in which the girdle was transversely wrinkled, throwing the 

 bristles into close groups. 



H. HANLEYI Bean. PI. 3, figs. 71-79. 



Shell oblong, convex, the lateral slopes nearly straight, the dorsal 

 ridge rather angular. Sculpture consisting of numerous rounded 

 tubercles, arranged in longitudinal rows on the central areas, the 

 series of tubercles finer and closer upon the jugum ; head plate and 

 lateral areas having coarser rather irregular tubercles. The lateral 

 areas are not raised. The mucro is median, rather elevated. 



The plates of insertion of posterior and intermediate valves are 

 obsolete, edges roughened ; anterior valve having a short, acute 

 insertion plate, outwardly rugose-sulcate, the sulci indenting, but 

 scarcely slitting the margin. Sutural plates moderate; sinus very 

 wide, denticulated by the sculpture of the outside. Eaves very 

 small. 



Girdle narrow, beset with numerous short and longer horn-col- 

 ored spicules. Length 10, breadth 5 mill., sometimes larger. 

 2 



