HALIOTIS. 83 



Comparison with the well-known H. rufescens Swains., will render 

 a figure unnecessary. A large specimen of Swainson's shell before 

 me has exactly the same superficial dimensions, but is only 2? inches 

 deep. H. ponderosa is nearly or quite destitute of the spiral waves 

 of H. rufescens, is of a darker red without, wants the inner margin 

 of the outer lip, and within has the clouds of iridescent colors 

 remarkably small and numerous, while in H. rufescens they are 

 remarkably large. It is more ponderous than any Haliotis which 

 we have seen, weighing 2 lbs., 2 oz., avoirdupois. (C. B. Ad.) 



H. assimilis Dall. PI. 22, fig. 29. 



Shell short-oval, very convex, the spire short but projecting above 

 the general outline of the back ; surface spirally Urate and having 

 low, rather obscure radiating waves ; perforations five ; inside sil- 

 very, with red, blue and green reflections. 



The form is the same as in H. corrugata, except that the spire is 

 more produced in the present species. It is solid and strong but not 

 very thick. The epidermis is dull reddish and greenish. Surface 

 sculptured by numerous spiral cords, alternately larger and smaller, 

 and obsoletely waved radiately. Below the row of holes there is a 

 shallow channel ; the area between the row of holes and the colu- 

 mellar margin is spirally Urate, and has an obtuse carina in the 

 middle. Inside light, the nacre silvery, red and green ; the muscle 

 impression is smooth in the specimens before me. Columellar plate 

 rather narrow, not at all truncated below, sloping inward. 



Length 110, breadth 82, convexity 34 mill. 



Monterey and San Diego, Cat., in deep water. 



Haliotis (J var.) assimilis Dall, Proc. U. S. Nat. Mus. i, 1878, p. 

 46. 



This is a smaller species than the other Californiau Abalones, and 

 curiously intermediate between them in its characters. It resembles 

 H.fulgens in having five open perforations, but differs from it in the 

 light tint of the nacre and the unequal spiral cords of the surface. 

 It is like corrugata in possessing quite a deep channel just outside of 

 the row of holes, but has a higher spire than that form, less rough 

 sculpture, a greater number of holes, and lighter nacre. Finally 

 we may compare H. rufescens, a species more nearly allied, but still 

 readily distinguished by its far thicker and larger shell, fewer holes 

 and other obvious characters. 



