52 



ECHINOIDEA. I. 



quite right. They belong to two different species, most likely also to different genera, and none of 

 them lias any relation to C. gracilis. 



The specimen from st. 219 has a remarkable form of tridentate pedicellariæ; the blade is long, 

 narrow, with nneven, finely serrate edge, deep and in the Iower part filled by a net of meshes. The 

 valve figured on PI. XIV. Fig. 20 is from one of the smaller pedicellariæ. I have only found this form 

 of tridentate pedicellariæ. The triphyllous pedicellariæ (PI. XII. Fig. 13) have a well developed cover- 

 plate with few holes; the edge finely serrate. The stalk of the pedicellariæ of the common strnctnre. 

 The spicnles are large fenestrated piates arranged in two well separated series; the sncking disk well 

 developed. Tlie tnbe feet are arranged in tliree series. None of the primary spines on the actinal side 

 are whole, so that nothing can be said of the way in which the point is formed; there is, however, 

 certainly no skin-bag ronnd the point. This species mnst probably form a separate genus. As, how- 

 ever, no quite sufficient characterization can be given of it liere, I shall propose no name for it, but 

 be contented with having pointed out that it has no relation to C. gracilis. 



The specimen from st. 184 has tridentate pedicellariæ somewhat recalling thoso. oiPhor vi osoma; 

 but they are distinguished from the latter by the faet that the widenings from the upper end of the 

 apophysis reach quite to the edge of the blade (PI. XIII. Fig. 26); (m Phoniiosoiiia they, as stated above, 

 end on the middle of the side of the blade.) The triphyllous pedicellariæ are similar to those of the 

 specimen from st. 219. The stalk of the jDedicellariæ of the common structure. The spicnles are 

 lengthened, narrow piates, arranged in 2 — 3 longitudinal series; no sucking disk is found. On the 

 actinal side the tube feet are arranged in a single regular line (on the abactinal side the arrangement 

 was indistinct in the specimen). All the primary spines on the actinal side are broken, so that the form 

 of the point cannot be decided. — That this species has no relation to C. gracilis or to the specimen 

 from st. 219 is evident. It seems to be nearly related to Ph.-^ foiuc, and would then have to be 

 referred, together with this latter, to the genus Ecliinosovia. (See farther down p. 57.) 



Althongh in the text Agassiz expresses a strong doubt whether the two species here men- 

 tioned, be really • A.> gracilis^ he nevertheless afterwards cites the stations from which they have been 

 obtained, among the localities of this species withoiit adding any interrogation; this way of iDroceeding 

 is very objectionable — and this is, unfortunately, not the only case. I shall express no opinion 

 whether the specimen(s) from st. 169 is really C. gracilis, as I have not seen it. It is not to be relied 

 upon with certaint\', until the pedicellariæ etc. have been exarained. 



«Astlicnosoiiia.^ /cnestraliuii Wyv. Thomson is by Bell (72, 73), and Koehler (229) thought to 

 be synonymous with v^.» Iiystrix. It has also to be admitted that there is a striking similarit}' as to 

 habitus between the two species; but a closer examination of the iDedicellariæ shows that the question 

 is so far from being of one species, that they will even have to be referred to different genera. — 

 There are three kinds of pedicellariæ, tetradactylous, tridentate, and triphjllous ones. The tetradac- 

 tylous ones, which have been so excellently described and figured by Wyv. Thomson («Porcupine» 

 Echinoidea. PI. LXVII. Figs. 5—6), are something quite unique among the Echinids, and consequeutly 

 an excellent character of this genus. Bell (72), to be sure, thinks it to be an abnormal form of pedi- 

 cellariæ, as he has not been able to find it in the numerous specimens he has examined. As, how- 

 ever, I have succeeded in finding this form also in A. coriaccuiu Ag., there can, of course, be no doubt 



