128 



ECHINOIDEA. II. 



rence of Spatangus ptirpureiia in American waters are due to confusion with Macropneustes. One 

 of the specimens in the U. S. National Museum Professor Rathbun most liberally sent me to Copen- 

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

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

 to be Macropneustes, though perhaps not all Alacr. spatangoides (see below). The specimen from 

 the Bermudas, taken b>- 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 pur pur ens does not occur at the American side of the Atlantic; in 

 any case it has not hitherto been found there. 



That the Spatangus of the Mediterranean {S. mcridionalis Risso, 5". regina: Gray) is identical 

 with the Spat, purpureus of the Northern Atlantic I quite agree with Agassiz, lyudwig, Koehler, 

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

 To be sure, Perrier (Op. cit. p. i8o) states that those of 6". vieridionalis are a little more elongate; 

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

 various degrees. The differences in the shape 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 Spatangus Raschi, which Norman has mistaken for the Mediterranean form. — 

 Judging from the material at my disposal of the Mediterranean form of Spat, pnrpiimis it can at most 

 be regarded as a rather indistinct variety. — The type of X spinosissii/ius Ag. I have not seen; but 

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

 Spatangus is known from the European seas to which it might be referred. («Espece deprimee»). 



A few words may here be said on Macropneustes spatangoides A. Ag. The pedicellarise are upon 

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

 pedicellarite are quite like those of 6". 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, purpureus. 

 The second form of tridentate pedicellarite (PI. XVI. Fig.s. 3, 13) differs from the corresponding form 

 in .S". purpureus in having the l)asal part sharply limited from the blade, the edge forming a distinct 

 angle between the basal part and the blade, whereas in S. purptiretis the one continues evenl\- into 

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

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

 as in Spat, purpureus. The ophicephalous pedicellarise (PI. 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 pedicellariie (PI. XVI. Fig. 15) are mainly like those of 6'. purpureus. The spicules are 

 irregular, more or less branched rods. — Tlie pedicellariai mentioned here were taken from the f-Chal- 



