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a number of specimens of a Pleiirechiims from East Asia, which likewise prove to 

 be a new species; it is described below as PL variegatus n. sp. — The description 

 of these new species may be preceded by a few notes on the two previously known 

 species, PI. bothryoides and ruber. 



Pleurechinus bothryoides Agass. differs from all the other P/eurec/iinus-species 

 in having a distinct, though small, lateral tooth on either side below the endtooth 

 in its globiferous pedicellariæ (PI. VI. Fig. 5—6). The basal part is narrow, without 

 produced outer corners, but otherwise rather variable in form, as shown by de 

 Meuere, who first described and figured these pedicellariæ („Siboga"-Echinoidea. 

 p. 77. PI. XVI. Fig. 267— (58). In this species also tridentate pedicellariæ occur. They 

 are small (ca. 02 mm. head), with the valves joining only at the point. The blade 

 is narrow, simple, widened at the point; the edge is straight, except in the widened 

 outer part, where it is coarsely sinuate and extremely finely serrate (PI. VI. Fig. 38. 

 PI. VII. Fig. 9). The ophicephalous and triphyllous pedicellariæ (PI. VII. Fig. 5, 51) 

 do not present any peculiar features. The buccal membrane contains rather nume- 

 rous bihamate spicules, and there is a border of small irregular plates round the 

 mouth. In the tube feet I have found no spicules. The spines are smooth, not 

 swollen at the point, ending in a more or less distinct central thorn. They have 

 two or three beautiful red bands in the outer part. There is a transverse line on 

 the genital plates. 



In the description of this species (Rev. of Ech. p. 465) Agassiz says: „There 

 are four deep disconnected pits of about equal size along the sutures of the plates 

 above the ambitus". Later on, in the „Challenger"-Echinoidea (p. 108) it is said: 

 „in the interambulacral area there are two disconnected elliptical pits at the two 

 extremities of the horizontal sutures", and the same is shown by the beautiful 

 figure (PI. X.a. fig. 2). These two statements are evidently contradictory and might 

 seem to indicate that the examples described in the „Challenger"-Echinoidea (and by 

 DÖDERLEIN) were not the same species as the type of PI. bothryoides described in 

 „Rev. of Ech.". As it was rather important to get this question settled, I asked 

 Prof. DouviLi.É if he would lend me the type specimen (from the collection of L'école 

 des mines in Paris) for examination. Prof. Douvillé most kindly sent me the pre- 

 cious specimen, for which service I beg him here to take my best thanks. The 

 type specimen (labelled „Coll. Michelin, Iles Gallopagos") proved to be an uncom- 

 monly large (40 mm. in diameter, 31 mm. high), beautiful, naked test of the species 

 figured in the Chall. Ech. and by Döderlein, having thus only two large^_deep, 

 disconnected pits along each horizontal interambulacral suture and one in each 

 ambulacral horizontal suture. The „four deep disconnected pits" Agassiz must 

 either have found by reckoning the whole width of the Interambulacra, or perhaps 

 he really saw such a form (such recent forms really existing — comp. „Pleurech.'' 

 variabilis and the new species of Opechinus described below) and then confounded 

 his notes of the two forms. The note that the type specimen of bothryoides is „in 



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