ECHINOIDEA. II. 155 



The triphyllous pedicellarise (PI. XVIII. Fig. 12) very much resemble small specimens of the 

 third form of tridentate pedicellarise, differing from them, however, in the blade being broader and 

 the basal part narrower. - - Ophicephalous pedicellarise do not occur, at least I have not found them 

 in any of the numerous specimens, which I have examined. --As for the tubefeet and the plates of 

 the disk reference must be made to Loven's very beautiful figures. Only a pair of spicules are 

 figured here (PL XVIII. Fig. 18). In some specimens the inner tubefeet of the anterior series of the 

 anterior petals are rather large, not of the shape of gills like the other tubefeet of the petals, and 

 full of spicules, whereas spicules are wanting in the transformed feet. In most specimens these tube- 

 feet are quite rudimentary. Genital papillae are sometimes very distinct. 



A few young specimens found among the vast numbers of larger specimens in our Museum 

 enable me to give some information -- though very far from complete -- of the postembryonal dev- 

 elopment of this species. The youngest specimen is scarcely 3 mm long; it shows as yet no trace of the 

 petals, and the same is the case in a specimen of 4 mm length. This is not in accordance with the 

 statements of Agassiz, who finds the petals distinct already in a specimen of only 3'6 mm length 

 (PI. XIX. Fig. 7. Revis. of Echini); only in specimens of ca. 8 mm I find the petals of a size corres- 

 ponding to that figured by Agassiz for a specimen of T > -6 mm . There seems then to be some error in 

 Agassiz' statement, either 3'6 is a printing error, or the specimen is not Br. lyrifera (comp. 

 the following remarks on the American specimens of i.Br. lyrifera}, as it can scarcely be supposed 

 that so considerable variation occurs in the development of the same species. (My young specimens 

 were taken in the Kattegat, where no other species of Brissopsis occurs, any error in the identification 

 being thus excluded). The suckers of the odd ambulacrum are well developed in the youngest speci- 

 mens, but can in no way be said to be enormous or even gigantic. The form of the peripetalous 

 fasciole is rectangular, as figured by Agassiz. In the youngest specimen the periproct is still close 

 to the peripetalous fasciole. It may be emphasized that the peripetalous and subanal fascicles are 

 quite without any connection even in the youngest specimen; no anal branches are developed from 

 the subanal fasciole. The latter includes in a specimen of 8'5 mm as yet only three ambulacral plates 

 and, accordingly, only two pairs of pores. In the specimen of 4 min length only two ambulacral plates 

 reach within the fasciole, the third reaching only the border of the fasciole; no pores (or tubefeet) are 

 as yet developed within the fasciole. How it is in the specimen of 3 ram I have been imable to see 

 with certainty. 



This species often shows curious monstrosities in the Danish Seas, as is also the case with Spa- 

 tangus purpureus and Echinocardium flavescens (Comp. above p. 124, 136). Meissner & Collin (Op. cit) 

 have figured a comparatively slightly monstrous specimen from the North Sea, and another is figured 

 by Doderlein (Op. cit PI. XXXIV. Fig. 7). Often the actinal plastron is formed in the shape of a 

 deep furrow in the bottom of which the spines are placed, the adjoining ambulacra forming a high 

 ridge on either side. Also the odd anterior ambulacrum on the abactinal side or even the anterior 

 half of the test may be quite sunken. In PL III. Figs. 2, 7, n some of these monstrosities are represented. 

 The suggestion that they are caused by some kind of parasitic organism seems not improbable, but 

 I have been unable to ascertain the fact. 



This species was taken by the Ingolf> at three stations only, viz.: 



20* 



