LYTECHINUS CALLIPEPLUS. 251 



interambulacra, especially around the tubercles or in the tubercles themselves, 

 and at the bases of the abactinal spines. 



The two specimens upon which this species is based are labelled " Echino- 

 metra lucunter, Florida. L. Agassiz," but in the catalogue both name and 

 locality are followed by a question mark. The specimens are obviously imma- 

 ture, but the description and figures here given show clearly they do not belong 

 in Echinometra. The buccal membrane is not plated nearly so heavily as in 

 other species of Lytechinus, but the globiferous pedicellarise indicate a probable 

 relationship with that group. When compared with specimens of L. variegatus 

 of the same size, the shape of the test, the characters of both abactinal system 

 and buccal membrane, the long primary spines, and the coloration all serve to 

 show that these little Echini cannot be the young of that species. And I have 

 failed to find any other known species to which they show any closer relation- 

 ship. They may prove to be the young of euerces, but the long primary spines, 

 the conspicuous primary tubercles and the low, flat test separate them rather 

 sharply from that species, as at present known. 



Lytechinus callipeplus, 1 sp. nov. 

 Plate 96, figs. 4-6. 



The largest specimen is a bare test, 11.5 mm. in diameter and 6 mm. high. 

 The abactinal system is 4 mm. in diameter and the actinostome is 6 mm. across. 

 The type is 8.5 mm. in diameter and 5 high, with the abactinal system not quite 

 3 mm. across and the actinostome, 4.5; the longest spine is 2.5 mm. long. In a 

 smaller specimen, 6.5 mm. in diameter, the longest spines are 3 mm. long. In 

 the largest specimen, there are 11 or 12 interambulacral, and 12 ambulacra! 

 plates in each column, while in the type, there are 10 or 11 and 10 respectively. 

 In a specimen, 7 mm. in diameter, the numbers are 9 and 9. 



The periproct (PI. 96, fig. 6) is moderately large, decidedly larger than a 

 genital plate. It is covered by about four plates of which the one adjoining 

 genital 3 is largest. The genital plates are about equal and are about as high 

 as broad. Each one carries a small tubercle near the proximal margin and 

 there may also be one or two miliary tubercles on the plate. The genital pore 

 is large and distinct at the distal end of the plate. The madreporic genital is 

 fairly well covered with the minute pores of the water system. The oculars are 



1 Ka\\ur7rAo = beautifully robed. 



