86 ECHINOIDEA. I. 



PrionecJiiiius and Trigonocidaris. Nevertheless its peculiar spicules and globiferous pedicellarise show 

 that the relation is not so very close. The globiferous pedicellarise are quite similar to those of 

 <iEchinusi> miliar is ^ but there can be no question of any nearer relation to this latter. On the other 

 hand this form of pedicellarias might indicate that it is a more primitive form than the other genera 

 here mentioned, in which the globiferous pedicellarise have only one unpaired lateral tooth. Also the 

 spicules indicate that it is a more primitive form; bihamate or similar regular spicules are otherwise 

 found in all <!.Echi7iid(e>^ and <iEchinoiiictrida'i (with the exception of Sfoiiiopneustes), but are wanting 

 in CidaridcB^ Salenidcs, DiadematidcB^ Echinothuridce^ and Arbaciadcr, where oul\- more or less irregular 

 fenestrated plates or thorn}- bows are found (Bell 50). Without entering on a nearer discussion of 

 the relationship of these forms, I shall here only give a table of the mentioned genera, which may, 

 I think, be of practical importance, as it is evident that these small forms have occasioned some diffi- 

 culties to the systematists. A facilitation of the determination will, I hope, lead to the discovery of 

 more related forms that may, no doubt, be found in the large, hitherto only little known tracts of the 

 ocean. That Genocidaris viaciilata has hitherto been overlooked in the Mediterranean, or at all events 

 misjudged, although it is, no doubt, rather commonly found in the Strait of Messina, presages that 

 we may still expect many new discoveries of these interesting small forms. 



Table of the Genera. 



1. The buccal membrane outside of the buccal plates covered by large plates. . 2. 



— — — — - — — — naked 4. 



2. The globiferous pedicellarise with the edges of the blade sharp, not connected 

 by cross-beams; several lateral teeth on either side. The spines strongly 

 thorny, those around the mouth curved ; the spicules a little irregular, three- 

 radiate, not bihamate Hypsiechinus. 



The globiferous pedicellaria; with the edges of the blade thickened, with 

 onh' one unpaired lateral tooth; the spicules bihamate 3. 



3. The test mucli grooved Trigonocidaris. 



— — not — Prionechinus. 



4. The globiferous pedicellarise with the edges of the blade almost quite coa- 

 lesced on the inside, so that only a series of small holes is left. One very 



large anal plate Gniocidaris. 



The globiferous pedicellarise with the edges of the blade thickened, but 

 not connected by cross-beams. No very large anal plate Arbacina. 



10. Hypsiechinus coronatus n. sp. 



PI. V. Fig. I. ri. VII. Figs. I— 20. PI. VUI. Figs. 5, 9, 15, 17, iS, 24, 25, 38. PI. XI. Fig. 6. 

 The test is flattened, more tlian twice as broad as high (the remarkably raised apical area not 

 included); the outline most frequentl)- beautiful!)- round, sometimes a little pentagonal. It is not 

 curved inward at the edge of the nK)Utli. The mouth-slits indistinct, the peristome large. The apical 



