44 SVEN LOVEN, ON POURTALESIA, A GENUS OF ECHINOIDEA. 



penicillate pedicels, belonging to the inner rows of the bivious ambulacra, the fasciola 

 Traversing their plates. The front ambulacrum, which is never seen to bear gills, has 

 simple locomotive pedicels, continuing all up to the calyx. But then in this genus the 

 l)eripetalous fasciola is absent. Brissopsis, Schizaster etc., on the other hand, are pro- 

 vided witli a peripetalous fasciola, and Echinocardium with an internal fasciola, and, 

 within the boundary of either, the frontal radius presents a set of peculiar pedicels 

 with crenulated or stellated disks, but outside of it only simple locomotive pedicels. 

 In Brissopsis and Schizaster the disks contain radiating lamintB, ') as likewise the finger- 

 like processes of Echinocardium. ^) The internal fasciola of this latter genus traverses 

 not (inly the front ambulacrum, but also the tops of the four petals, and the apical 

 ])iirts of these that fall Avithin the fasciola, bear no branchial leaflets, only very minute 

 simple pedicels. 



The penicillate circum-oral pedicels of the five ambulacra Johannes Mulleb found 

 similar in all the genera examined, and, in all of them, subanal penicillate pedicels, in 

 Brissopsis, as stated above, three on either side within the sub-anal fasciola, in Schiz- 

 aster canaliferus, which is prymnadete, seven on either side, at a distance from the 

 periproct, not between it and the posterior fasciola, but in front of the latter. 



To this account may be added the previous researches of Erdl and Valentin, 

 and those of subsequent observers, as Al. Agassiz, Hoffmann and Perkier. ^) 



In my former memoir on Echinoidea I abstained from entering upon any detailed 

 description of these organs, and gave only a short notice of their structure and distri- 

 bution in Brissopsis lyrifera ■*), and of the primordial pedicels in Toxopneustes dros- 

 bachcnsis '')• I expected to have, sooner or later, richer materials to examine. Although 

 this liope has but partially been realised, as it is of some importance to compare the 

 pedicels of Pourtalesia to those of the Spatangida?, in pai-ticular, and as I shall have 

 no more occasion to revert to the subject, I here give what has hitherto been attainable 

 to me, from which it will appear that these organs, overlooked as they have been, 

 are well worth a much closer investigation than what I have been able to bestow 

 upon them. 



To the whole region around the peristome Desor gave the name of njioscellen ''), 

 retaining that of nphi/Uode» for the part of each ambulacrum contiguous to the stoma, 

 often distinguished by a somewhat expanded surface, and always by the presence of 



>) 1. c. pi. Ill, fig. 6, 7. 



-) 1. c. p. 29, pi. Ill, fig. 4, 5. 



') Valrntin, in Agassiz, Moiiographies d'Echinotlennes, IV, p. 37, pi. 4, Echiiuis; 1842. — Ekdl, Wieg- 

 manns Archiv, VIII, 45, Taf. II, uEchinus saxatilis"; 1842. — Alex.\ndeii Agassiz, Ilev. of tlio Echinidiie, 

 I, p. 693, with numerous figures. — Hoffmann, Znr Anatomie der Echinen u. Spatangen, Niederlan- 

 disches Arcliiv fiir Zoologie, I, 1871, p. 75, 80. pi. X, fig. 78, 88 — 90. — Perkier, Recherches sur 

 ies P^dicellnires et les Ambulacres des ast^ries at des oursins; deuxieme partie, Ann. d. Sc. nat., 5:me 

 ser., XIII, l870, p. 1, 61: Ech. irreguliers ; pi, 6, fig. 2, 8, 5: Araphidetus; 4, c — e, 7, c: Spatangns; 

 6, 8, 9: Brissopsis; 10: Brissus; ib. XIV, n;o 8: Eehinoneus. 



*) Etudes, p. 10, pi. I, fig. 1. 



•■) Ib. p. 27, pi. XVII, fig. 149—152. 



*) Synopsis des Ecliinides fossiles, 1858, p. 247. In creating these appellations Desor had in view the 

 Cn-isiduiidse alone, but they are equally applicable to the corresponding parts of the Spatangidne. 



