334 ECHINONEUS SEMILUNARIS. 



has perhaps more properly retained the name E. semUtmaris Lam., which 

 was adopted by Duchassaing, and which has been given by Desor, with some 

 doubt, to a species collected at Trinidad. I would retain for the species from 

 the Sandwich and Kingsmills Islands the name cyclostoinus ; to judge from 

 the description of the color given by Desor to his E. serialis, the Sandwich 

 Island species may prove identical with it ; this name is scarcely appli- 

 cable, being based upon an arrangement of the ambulacra! tubercles, 

 which is frequently met with in specimens of the two species. As far 

 as I am able to discriminate between the tests of these two species, the 

 Pacific species is remarkable for the narrowness of its poriferous zone (PL 

 XIV f. ?'), the pores being placed in close contact, separated by a ridge 

 carrying small tubercles, while in the specimens of E. semilunaris the porif- 

 erous zone is much broader (Pi. XIV. f. S). It has also (taking the same 

 point of the test in specimens of the same size) larger tubercles, and a 

 greater number of large glassy tubercles (PL XIV. f. ?'), while the miliaries 

 are closely crowded together. In E. semilunaris, on the contrary (PL XIV. 

 . the primary tubercles, as well as the glassy tubercles, are proportionally 

 much smaller and farther apart, the miliaries being more numerous. From 

 an examination of the alcoholic specimen from Florida, I could not come to 

 any satisfactory conclusion concerning the function of the glassy tubercles; 

 they are not primary tubercles in the course of growth, as they are fully 

 as large, and the primary tubercles, when young, always appear at first as 

 opaque tubercles. They carry no special spines. On Living specimens their 

 function will probably he ascertained. Similar glassy tubercles often appear 

 on the edge of very young Clypeastroids (Clypeaster subdepressus), which 

 disappear in older stages. Desor lias given figures of the spines; but, in addi- 

 tion to these, the test is thickly covered with stout pedicellarise carried upon 

 moderately long peduncles. The tentacles do not differ (PL XIV. /'. .' ) (as Un- 

 as could be judged from this alcoholic specimen, where they were still tolerably 

 expanded) from the tentacles of ordinary regular Echini, haying prominent 

 sucking disks. The tentacles retain the same structure from the mouth to the 

 apical system. On the lower surface, especially round the month and anal sys- 

 tem, the spines are longer and more slender (PL XI V.f. ', ) than on the remain- 

 ing portions of the test. The anal system will. I think, furnish good characters 

 for the determination of species, if we can judge from the striking differences 

 the arrangement of the plates of the anal system presents in the two thus far 

 examined. In the Pacific species (PL XIV. f. G) the anal opening is more 



