86 ECHINOIDEA. I. 



Prioncchimis and Trigonocidaris. Nevertheless its peculiar spicules and globiferous pedicellariæ show 

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

 <!.Echmus» miliaris^ but there can be no question of any nearer relation to this latter. On the other 

 band this form of pedicellariæ might indicate that it is a more primitive form than the other genera 

 liere mentioned, in which the globiferous pedicellariæ have only one inipaired lateral tooth. Also the 

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

 found in all <tEchinidæy> and <iEchinonietridæy> (vvith the exception of Stomopnciistes), but are wanting 

 in Cidaridæ^ Salenidæ^ Diadematidæ, Echinothuridæ, and Arbadadæ, where onh- more or less irregular 

 fenestrated piates or thorny bows are found (Bell 50). Without entering on a nearer discussiou of 

 the relationship of these forms, I shall here onl}- give a table of the mentioned genera, which mav, 

 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 hoi^e, lead to the discovery of 

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

 ocean. That Genocidaris iiiaciilafa 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 piates covered by large piates.. 2. 



— — — — - — — — naked 4. 



2. The globiferous pedicellariæ 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 moiith curved ; the spicules a little irregular, three- 



radiate, not bihamate Hypsicckimis. 



The globiferous pedicellariæ with the edges of the blade thickened, with 



only one unpaired lateral tooth ; the spicules bihamate 3. 



3. The test much grooved Trigonocidaris. 



— — not — Prionechinus. 



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

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



large anal plate Genocidaris. 



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

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



10. Hypsiechinus coronatus n. sp. 



PI. V. Fig. I. PI. VII. Figs. I— 20. PI. VIII. Figs. 5, 9, 15, 17, iS, 24, 25, 3S. PL XI. Fig. 6. 

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

 included); the outline most frequently beautifulh- round, sometimes a little pentagonal. It is not 

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



