i:<HINUS. 123 



j 1. Km i NTS SPHJIRA. Plates XXXI . XXXII., figs. 1-11. 



While alive this animal is at least five inches and a half in diameter, 

 computing from tin- opposite extremities of the spines, all the parts Ix-ini: 

 in vigorous, regular, ami symmetrical order. 



It may be then circumscribed by about three-fourths of a sphere. 



are more nearly globular, from the greater equality of the vortical 

 ami transverse axis, while, from greater inequality, specimens appear dLs- 



1. But, for the most part, all individuals of the race are surprisingly 

 symmetrical. 



This creature, as IB well known, consists of on external shell, con- 

 fminji the intestinal parts, wholly invested by an infinity of hard, sharp, 

 moveable spines, resembling those of the terrestrial hedgehog, whence its 

 name is dcri 



Numerous flexible cords or suckers protrude from among the spines, 

 aUmt double- their length or more, which extend until reaching sonic solid 

 substance. The extremity of each then flattens, broadens, and applying 

 firmly, they assist the- subject In traversing its prison. Plate XXXI 

 fig. 1, a, a. 



To understand the nature of all this, we must view the naked shell 

 to find a double set of organs, as above, the spines and suckers. 



A multitude of low spherical segments project from its surface, of all 

 different dimensions. These sustain the basis of the spine's, which play 

 on them somewhat as a boll and socket. This part may be therefore 

 \ iewed as corresponding to the articulation of the bones of other animal.-. 



Next, the substance of the whole shell is penetrated by a multitude 

 of minute pores, disposed in rows and comportments, for protrusion of the 

 long flexible cords, which ore so many suckers, from within. These ore 

 pro|M-rly the instruments of progression. 



Let us suppose a specimen at rest. All the suckers are retracted 



within or close on the shell, and the spines motionless. A few of the suckers 



now protrude ; they search around for a solid foundation, others follow 



them : at length many are employed, and the animal is fixed securely in it.- 



Uut to change it, those lx.-hind ore relaxed, while the contraction 



