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 

 peripetalous fasciola is absent. Brissopsis, Schizaster etc, on the other hand, are pro- 

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

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

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

 In Brissopsis and Schizaster the disks contain radiating laminas, ^) as likewise the finger- 

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

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

 parts of these that fall within the fasciola, bear no branchial leaflets, only very minute 

 simple pedicels. 



The penicillate circum-oral pedicels of the five ambulacra Johannes Muller 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 

 ])eriproct, 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 riotice of their structure and distri- 

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

 bachunsis "). I expected to have, sooner or later, richer materials to examine. Although 

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

 pedicels of Pourtalesia to those of the Spatangida?, in particular, and as I shall have 

 no uiore 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 aiiuch closer investigation than what I have been able to bestow 

 upon them. 



To the whole region around the peristome Desor gave the naine of i]/loscelle)'> "*), 

 retaining that of ))ph?/llode» for the part of each ambulacrum contiguous to the stoma, 

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



1) 1. c. pl. III, fig. 6, 7. 



-) 1. c. p. 29, pl. III, fig. 4, 5. 



^) Valentin, in Agassiz, Monographies d'Écliinoflennes, IV, p. .37, pl. 4, Echinus; 1842. — • Erdl, AVieg- 

 raanns Archiv, VIII, 45, Taf. II, »Echinus saxatilis"; 1842. — Alexander Agassiz, Rev. of the Echinidfe, 

 I, p. 693, with numerous figures. — Hoffmann, Zur Anatoraie der Eohinen u. Spatangen, Niederlän- 

 disches Archiv fiir Zoologie, I, 1871, p. 75, 80, pl. X, fig. 78, 88 — 90. — Perkier, Eecherches sur 

 les Pédicellaires et les Ambulacres des astéries et des oursins; deuxiéme partie, Ann. d. Se. nat., 5:me 

 sér., XIII, 1870, p. 1, 61: Ech. irréguliers; pl. 6, fig. 2, 3, 5: Amphidetus; 4, c — e, 7, c: Spatangus; 

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



*) Études, p. 10, pl. I, fig. 1. 



5) [b. p. 27, pl. XVII, fig. 149—152. 



^) Synopsis des Échinides fossiles, 1858, p. 247. In creatiug these appellations Desor had in view the 

 CassidulidtB alone, but they are equally applicable to the eorresponding parts of the Spatangidie. 



