88 ECHINOIDEA. I. 



foot, with the opening directed towards the moiith. The two buccal tube feet are not placed in quite 

 the same line, bnt one a little oiitside of the other; this is most distinctly seen in younger specimens, 

 and in quite small young ones of a diameter of up to 2—3™" only one tube foot of each pair is devel- 

 oped at all. Also in a single specimen of a diameter of 6'"'" onh- one tube foot of each pair of moutli- 

 feet is develojjed; sometimes it may also be seen that one tube foot is quite wanting in one pair, 

 rudimentar}- in another, while both the tube feet are well developed in the other pairs. — A similar 

 feature is found, as stated by Agassiz, in Prioncchinus , or, at all events, in a form by Agassiz 

 wrongly referred to Prionrchmiis (see above p. 82 — 83). Spicules are not found in the buccal membrane, 

 the small gills contain the common irregular calcareous piates (PL VII. Fig. 12), onh', however, in the 

 basal part; spines or pedicellariæ are not found on the buccal membrane. 



The apical area is ver\' peculiar, especially in J — a well marked sexual difference being found. 

 In (? the apical area is only slightly raised in the middle (PI. VII. Fig. 9); the ocular piates are small, 

 all widely separated from the periproct, the genital piates are much larger, truncate, rather regularh' 

 septangular, only the boundary line towards the ocular piates somewhat curved. Each genital plate 

 has one rather strong tubercle or a pair of such tubercles at the inner edge, the ocular piates are 

 quite smooth, or more rarely with a few, very small miliary tubercles. The genital pore is very small, 

 situated about in the middle of the plate. The madreporite is very little conspicuous, has only few 

 (2 — 3) pores. The periproct is covered by one larger plate and some smaller ones; in quite small speci- 

 mens the large plate covers the whole periproct. 



In 5 the mutual relation of the piates is chiefly the same as in (?, but the ocular piates and 

 especially the genital ones have been very much elongated and bent upward, so that the whole ajjical 

 area is raised like a knob. The lower part of the genital piates and the ocular jDlates in their whole 

 extent are quite smooth, but the inner (upper) part of the genital piates is very riclily set with 

 tubercles forming, as it were, a crown round the upper edge of the knob (PI. VII. Fig. i). The peri- 

 proct as in (?, without tubercles. The genital pores are large, and situated nearer to tlie outei 

 (lower) edge. 



Of pedicellariæ only three kinds are found: globiferous, ophicephalous, and tripliyllous pedicel- 

 lariæ. Tridentate pedicellariæ are wanting — at all events in the specimens in band. The globiferous 

 pedicellariæ (PI. VII. Figs. 19, 20) remind very much of those in -.EchimtS' miliaris. The upper ends 

 of the apophysis continue directly in the edges of the blade, which are sharp and run out into 2—4 

 teetli on either side; there are no cross-beams connecting the edges across the hollow inside of the 

 blade; the end-tooth especially large, of the structure t\pical in the Ecliinids. The glands are quite 

 small reaching only to the basal part; no neck. The ophicephalous pedicellariæ (PI. VII. Fig. 18, 

 PL VIII. Fig. 38) have a quite .short neck, but otherwise they do not, any more than the triphyllous 

 pedicellariæ (PL VII. Fig. 16), show conspicuous peculiarities. It is, however, to be noted that in the 

 triphyllous pedicellariæ the edge is c^uite .smooth. — The stalks of the pedicellariæ consist of longi- 

 tudinal fibres connected by cross-beams to a ratlier compact reticulation ; they are not hollow; they 

 increase evenly in strength downward, but are not widened at the base. — The sphæridiæ (PL VII. 

 Fig. 17) show no marked peculiarities; they are slightly spinulous in the point, short-stalked, often 

 somewhat irregular, and more globiform than the figured one. 



