NO. 3 CASSIDULOID ECHINOIDS — KIER 1 83 



specimen it is almost on the posterior margin. Furthermore, on the 

 smallest specimen the periproct is higher, with an oblique opening, 

 as opposed to the almost vertical opening in the larger specimens, 

 and the opening is larger relative to the size of the test, the width of 

 the opening being 21 percent of the length of the test in the smallest 

 specimen but only 15 percent in the largest. 



Floscelle. — In the smallest specimen the bourrelets are slightly 

 developed, with the result that the peristome is oval transversely and 

 not subpentagonally angular as in the larger specimen. The phyllodes 

 are very slightly developed, with no widening and with only slight 

 crowding of the pores, with only one or two pores slightly displaced 

 from each series. In the specimen (text fig. 154) 21 mm. long, in 

 ambulacrum II the pores are much more crowded, with three pores 

 occluded in each series, on the specimen 35 mm. long (text fig. 155) 

 four pores are occluded, and on the specimen 55 mm. long there are 

 six (text fig. 156). The phyllodes also increase relatively in width. 



Tuherculation. — It is particularly interesting to note that the tuber- 

 cles in the smallest specimen are approximately the same size as they 

 are in the largest. There is very little growth in a particular tubercle 

 as the echinoid grows. Accordingly, the tubercles on the smallest 

 specimen are very large relative to the size of the test. Presumably 

 the spines would be very large on the smallest specimen also, but 

 not enough spines are preserved on this specimen to be certain. 



Habitat. — According to A. Agassiz (1873, p. 555), this species 

 lives on sandy beaches, from 5 to 6 feet below low-water mark, half 

 buried in the sand up to the extremity of its petals. 



Occurrence. — Recent of American west coast. 



Location of type specimen. — Museum of Comparative Zoology, 

 Harvard. 



Synonym of RHYNCHOLAMPAS 



Anisopeiahis Arnold and Clark, 1927. Mem. Mus. Comp. Zool., vol. 50, No. i, 

 p. 44. Type species by original designation, Anisopctahis ellipticus Arnold and 

 Clark. 



DESCRIPTION OF TYPE SPECIES 



RHYNCHOLAMPAS ELLIPTICUS (Arnold and Clark) 



Plate 29, figures 1-3 ; text figure 153 



Anisopetalus ellipticus Arnold and Clark, 1927. Mem. Mus. Comp. Zoo!., vol. 50, 

 p. 45, pi. 6, figs. 16-20. 



Material. — The holotype and six other specimens were studied. 

 Shape. — Medium size, holotype 50 mm. long, elongate, with 



