89 



Pleurechinns macuiatns n. sp. (PI. I. Figs. 4, 14). This species very closely 

 resembles PL bothnjoides in the form and structure of the test. The pits are some- 

 what variable in size, sometimes not reaching to the base of the primary tubercle; 

 those at the outer edge of the ambulacral areas are generally less distinct than in 

 bothryoides. There is a well developed covering membrane along the edge of the 

 pits, which will probably be found to be the case also in bothryoides. (Comp. Duncan. 

 On the genus Pleurechinus.) The pits at the inner edge of the ocular plates likewise 

 are somewhat variable in size. The genital plates (PI. II. Fig. 5) have the outer 

 part, with the genital opening, depressed and marked off from the inner part by 

 a sinuate transverse line, as is the case also in bothryoides and variegatus. It is 

 especially distinct in smaller specimens. The anal opening is central or subcentral; 

 the plates of the periproct are rather large, and the anal plate is distinct. The 

 spines are smooth, generally distinctly knobshaped at the tip; the actinal ones are 

 widened and curved. — The globiferous pedicellariæ (PI. VI. Fig. 20, PI. VII. Fig. 17) 

 have no lateral teeth, only a small rounded knob on either side; only in one in- 

 stance have I found the lateral teeth distinctly developed); the outer corners of the 

 basal part are marked but not produced. Upon the whole the form of these pedi- 

 cellariæ, however, is not very constant. Tridentate pedicellariæ are found; they 

 are like those of bothryoides, and the same holds good for the ophiceplialous ones; 

 the triphyllous pedicellariæ (PI. VI. Fig. 44) have the blade more widened than in 

 bothryoides. 



The colour is very variable; the test may be uniformly gray, with some 

 indistinct white spots, or white with reddish spots or even quite white; sometimes 

 it is violet or red. The spines are uniformly whitish, reddish or violet or with a 

 pair of faint reddish bands. 



This species is the „Temnopleurus bothryoides'- of Bell') from Macclesfield 

 Bank. I have also seen specimens from Hongkong (Hamburg Museum), Torres 

 Strait (Haddon) and from the „Siboga"-Stations 43, 99, 164, 258 and 315 (?). It is 

 evidently closely related to PI. bothryoides and perhaps ought to be regarded only 

 as a variety of that species. But in any case it must be kept as a distinct form ; 

 whether it then be regarded as a separate species or only as a variety, is of very 

 little importance. — From siamensis, to which it may also have considerable resem- 

 blance, it is distinguished by the transverse line of the genital plates and by the 

 tubercles forming horizontal rows; the latter feature, however, is of course not seen 

 in very small specimens. — It is a rather large species, though, probably, it does not 

 reach the size of bothryoides. 



The number of species of the genus Pleurechinus having thus been increased 

 from 2 {PI. bothryoides and ruber, the species variabilis Döderl. not really belonging 

 to this genus) to 7, it will be very useful to give an analytical table of the species. 



M Echinoderms of Macclesfield Bank. p. 41U. 



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