128 ECHINOIDEA. II. 



rence of Sfafaiigns piirpureus in American waters are due to confusion with Macropneustes. One 

 of the siiecimens in tlie U. S. National Mnseum Professor Rathbnn most liberally sent me to Copen- 

 hagen for examination, the others I examined dnring my visit to America last summer. I likewise 

 had then occasion to examine specimens in the collection of Yale College. All these specimens I fonnd 

 to be Alacropneustes, though perhaps not all Ålacr. spatangoidcs (see below). The specimen from 

 the Bermudas, taken' by the «Challenger », I have examined in the British Museum; it is likewise 

 Macropneustes (the characteristic branching fasciole is distinctly developed). It may then be taken 

 as rather certain that Spatangus p-itrpurciis does not occur at the American side of the Atlantic; in 

 any case it has not hitherto been found there. 



That the Spafangiis of the Mediterranean [S. iiteridio>ialis Risso, 5. rcginæ Gray) is identical 

 with the Spat. pjirptiretis of the Northern Atlantic I quite agree with Agassiz, Ludwig, Koehler, 

 Bell a. o. In the pedicellariæ no difference between the Mediterranean and the northern form is found. 

 To be sure, Per ri er (Op. cit. p. i8o) .states that those of S. iiicridionalis are a little more elongate; 

 but he has certainly seen only a few pedicellariæ, otherwise he must have found them elongate in 

 various degrees. The differences in the sliape of the test pointed out by Philippi and Sars (Op. cit.) 

 are not constant, though I agree that the Mediterranean form is generally a little more arched than 

 the northern form; the latter is often as high as the Mediterranean form, but it is generally more 

 sloping towards the ambitus. Norman (Op. cit.) points out several other characters, which would cer- 

 tainly distinguish the Mediterranean form as a good species — but, as is already pointed out by 

 Hoyle (Op. cit), it is Spatangtis Rasclii, which Norman has mistaken for the Mediterranean form. — 

 Judging from the material at my disposal of the Mediterranean form of Spat. pur pur eus it can at most 

 be regarded as a rather indistinct variety. — The type of ^. spinosissinnis Ag. I have not seen; but 

 it cannot be doubted that it is identical with piirpureus, since no other low species of the genus 

 Spatang2is is known from the European seas to which it might be referred. («Espéce deprimée»). 



A few words may here be said on Macropneustes spatangoidcs A. Ag. The pedicellariæ are upon 

 the whole very like those of Spat. purpureus. but some differences may be noticed. The tridentate 

 pedicellariæ are quite like those of >S". purpureus except the largest forms (PI. XVI. Figs. 20, 33) which 

 have the outer, widened end of the blade shorter and more spoonshaped; the edge is bent strongly 

 inwards at the lower end of the widened part; the keel of the blade is not distinct. The stalk is very 

 short and thick, the neck quite short. This large form (2'°™ head) I have not found in Spat. pur p2ir eus. 

 The second form of tridentate pedicellariæ (PI. XVI. Fig.s. 3, \t^) differs from the corresponding form 

 in i', purpureus in having the basal part sharply limited from the blade, the edge forming a distinct 

 angle between the basal part and the blade, whereas in i", purpureus the one continues evenly into 

 the other without a distinct angle. The blade is rather small, though not so small, generally, as in the 

 figured one. Elongated specimens of this kind of pedicellariæ (i"'™ head) (PI. XVI. Fig. 30) are found 

 as in Spat. purpureus. The ophicephalous pedicellariæ (PL XVI. Fig. 4) are rather different from those 

 of purpureus, the blade being shorter and the basal part being more developed than in that species. 

 The triphyllous pedicellariæ (PI. XVI. Fig. 15) are mainly like those of S. purpureits. The spicules are 

 irregular, more or less branched rods. — The pedicellariæ mentioned here were taken from the Chal- 



