12 SVEN LOVEN, ECHINOLOGIOA. 



dnced into iive liuge, .solitary, equidistant, acetaLulated, pro- 

 visional suckers, and niiderneatli the base of eaeh of these 

 one pair of mucli smallei' ambulacral pedicels, tlie priinordial, 

 persistent pair. has made its ap])earance, while oii the ventral 

 as well as on the dorsal side of tlie body tlie spines liave at- 

 tained some lengtL. Bnt no forcipes were seen and I looked 

 in vain for the water-pore which was observed by Bury. Witli- 

 in the envelope the skeleton of the imago had begun to form.* 

 On the dorsal side, before the specimen was löst by accident, 

 the five eostals of the ealyx were seen and sketohed, five large 

 and thin reticular laminu' placed near tlie periphery interme- 

 diately to the provisional suokers, as shown by Bury. On 

 the ventral side, \vood-engra\'ing iig. 1 — 4, the faithful drawing 

 of the commencing skeleton was tinished. The five primordial 

 pairs of ambulacral plates, I, II, III, IV, V, had made their 

 appearance, ten contiguons lamels, eaeh affording a pore for 

 the passage of the ducts of one pedicel. Externally eaeh pair 

 is in close contact witli the basis of one of the solitary pro- 

 visional suckers, there being vet no second pair of ambula- 

 crals inter\ening. Outward, close to the periphery. on the 

 line intermediate between every two pairs, the Iive ])rimary 

 solitär}^ plates of the interradium are forthcoming. AMien I 

 first obse]'ved them, unacquainted as I then was with the fact 

 of their solitary beginnings, I was much puzzled at being 

 unable to make ont more tlian one single first plate in every 

 interradium. They are. here as in the Cidarid, excluded 

 from the primordial ambulacral circle. But when this will 

 have been followed by a second circle, they will take their 

 places between its five pairs, and then this second circle, the 

 first peristome, will come to consist of five binary ambulacrals 

 and five solitary interradials. even as in the Cidarid, Fl. II, 

 fig. U. This, as has been remarked, is its fundamental con- 

 stitution in the wdiole class. iVnd outward of this circle will 

 be added gradually, eaeh plate in close contact with the pre- 

 ceding, of ambulacrals a second circle of five pairs, then a third 

 and so on, every new plate giving passage to the ducts of one 

 pedicel; and while, at the same time. in eaeh interradium the 

 solitary first plate will be followed, not by another solitary 

 one, but by a jiair of plates and this by another and so on. 



Etudes s. 1. Echinoidées. p. 27, Pl. XVII, tig. 141—152. 



