666 PEDICELLARISE. 



In the Petalosticha the genera which have been examined show a much 

 greater uniformity of plan. The pedicellarise of the Echinonidae resemble 

 the short type of tridactyle pedicellarise of Clypeaster, with a somewhat 

 longer, flexible, muscular shaft (PI. XV. f. .'). In the Cassidulidae the only 

 pedicellarise observed are figured on PI. XVI. f. 15 ; they resemble the small, 

 tridactyle, short-stemmed pedicellarise of Spatangus. Very remarkable pedi- 

 cellarise have been described in Pourtalesia ; they are figured on (PI. XVIII. 



f. 16- 18). 



In the genera Echinocardium (Pis. XXV., XXVI.) Lovenia. Leskia, 

 Breynia, Spatangus, Maretia, Brissus, Schizaster, and Metalia, of which I 

 have examined pedicellarise, we find a remarkable uniformity of type, and 

 very slight differences among the different families. We can reduce them 

 to two types, in one of which the heads consist of more or less slender 

 prongs, leaving -wide open spaces {PI. XXVI f. 37), resembling the gem- 

 miform type of the Echinidae and Echinometradae, but of which the tips 

 are merely serrated, and never carry large terminal hooks; this type is the 

 most common among the Spatangoids, and is found in Echinocardium (PI. 

 XXVI. f. 19 ; PI. XXV. f. so), Lovenia {PI. XXV f. 31 ; PI. XXVI. f. 36), 

 Breynia {Pi XXV. f. 82), Maretia 1 PI XXV. f. S3, SJ, ; PI XXVI. J. 21, 22), 

 Meoma (PI. XXVI. f. 28, 29, S3, .:.',), Brissus ( PI XXVI. /. 38), and in Schi- 

 zaster {PI XXVI. f. 41, 42). The other includes what we may call the ordi- 

 nary tridactyle type, with a stout head, broad base, and short stem, such as 

 we find in Spatangus {PI XXVI f. 23, «; PI XXV. f. 85), and the long- 

 headed, small-based, long-stemmed, tridactyle pedicellaria, with smooth or 

 serrate edges, occurring in Echinocardium (PI. XXV. f. 26, 27% in Spatangus 

 (PI. XXVI /. 26,27), in Meoma {PI XXVI. f. 80, 31, 82), and in Schizaster 

 (PI. XXVI f. 40); we may have serrations taking the place of lateral pro- 

 cesses, as in Brissus (PI. XXV. f. 36, 37). Another kind of pedicellarise, 

 which we might strictly call the typical trilobate pedicellariaa, is character- 

 istic of the Spatangoids proper (PI. XXV f. ..v, ',:; PL XXVI. f. 24); the 

 short tridactyle pedicellariae of Clypeaster recall them to a certain extent. 

 These pedicellarise are gibbous at the base, contracted in the central part, 

 which is prominently serrated, and terminates with a broad spoon-shaped 

 tip (PI. XXV. f. 26"). In the pedicellarise of the Spatangoids the soft parts 

 are but scantily developed. 



In the greater number of starfishes the pedicellarise are supported upon 

 comparatively short stems, and are, as in our common starfish (Asteracanthion), 



