ECHINOIDEA. I. 123 



pedicellariæ thev are so \-er\- similar to alhiis, that herein scarcely any specific difference can be pointed 

 out. In gibbosus, however, I have onl\- seen a small form of tridentate pedicellariæ (PI. XVII. Fig. 12); 

 bnt I suppose that also the pecnliar large form is fonnd in tliis species, and likewise mav perhaps 

 the small form be fonnd in the two other species, although I have not found it. It is, however, to be 

 noted that gibbosiis has only 4 pairs of pores, while the two others have 7— S pairs; and so it would 

 be no Strange thing, if its tridentate pedicellariæ were different from those of the others. As in 

 albus only very few bihamate spicules are found. Agassiz (Rev. of Ech. p. 444) states that tliree 

 ocular piates reach to the periproct; on the specimen I have examined (- Challenger.« st. 304, western 

 coast of Patagonia), no ocular plate reaches to the periproct. The same faet holds good with regard 

 to bullatiis. (Of Str. bullatiis I have examined the type specimens in British Museum, of albiis a couple 

 of specimens are found in the museum of Copenhagen.) 



That these species are nearly related is quite undoubtful, and it is as sure a faet that they have 

 nothing to do with the real Sfro!igyloccnfrof?cs-?,Y>&ci&s. They must form a separate genus getting the 

 name oi Loxccliiiius Desor'), which has just been established for Ecliinus» albus Mol. As already 

 mentioned the globiferous pedicellariæ are constructed as in ParccJiiiiiis [miliaris etc), apart from the 

 short neck, and I must regard these two genera as closely allied, so that Loxccliiyuts is chiefly to be 

 regarded as a polypore Parccliiiius. That the whole habitus of the /.c.r<:'f/««?/.9-species recalls Par- 

 cchinns very much, speaks, of course, together with the other features, also in behalf of such a rela- 

 tion, although a similar habitus alone in no wa\- can be regarded as a proof of near relationship 

 (comp. Psciidocentrohis dcprcssiis and Aufliocidaris JwiiinlostomaX 



Strongylocciifrofus lividus (Lamk.). Of this species, which is so well known cspecially by the 

 examinations of Valentin, I can give no new informations; I shall only liere mention the features 

 which in mv opinion are of essential importance for the determination of its systematic position, but 

 which are generaliv omitted in the systematic descriptions. A primary tubercle is found ou all the 

 ambulacral piates; in the lower ambulacral piates there are only tliree pairs of pores. In the smaller 

 specimens all the ocular piates are sliut off from the periproct, in the larger ones ene or two iiia\' 

 reach to it. The buccal membrane contains ratlier few fenestrated piates; most of those outside of the 

 buccal piates are thick, round, and carry pedicellariæ; nearest to the edge a sphæridia may be found, 

 sometimes one more ma\- be found farther in 011 the buccal membrane. There are no spines 011 the 

 buccal piates or 011 the other piates of the buccal membrane. To be sure Valentin savs (Anatomie 

 du genre Echinus. p. 62) : il existe eiicore å la surface de la membrane buccale de petits piquants 

 microscopiques , dont la structure ne différe en rien de celle des piquants*; but I suppose it to be 

 stalks of pedicellariæ lie has mistaken for spines. (_)ii the figure to which lie refers, 110 spines are 

 found, but only stalks of pedicellariæ. The globiferous pedicellariæ are most nearly alike to those of 

 Parechinus. The blade is quite open with i — i lateral tooth (PI. XVII. Fig. 19), but the edge is thick, 

 not thin and sliarp as in Parrc/iiiius. There is no neck; the stalk consists of long, thin threads, only 

 little connected, except at the eiids of the stalk. (Also in the other pedicellariæ the stalk is con- 

 structed in this manner.) The tridentate pedicellariæ are very pecnliar with long, narrow blade, 

 coarsel}- serrate through the whole edge (PI. XVII. Fig. 21); there are 110 small teetli. Tlie opliicc- 



I) Synopsis des Ech. fossiles, p. 136. 



1 5* 



