Cidaris. RADIATA. ANOCYSTI. 477 



the sockets of the teeth. According to this author, the water enters 

 the perforated suckers, passes along the five tubes, and escapes at the 

 mouth. Future observation, however, will probably assign an oppo- 

 site direction to the current, and the perforated tubes on the oral disc 

 as the orifices at which the water enters. The organs of reproduction 

 appear to be limited to five ovaria, intimately connected, and opening 

 by five oviducts, in the perforations of the five plates of the pelvis. 

 When in season, the roe fills a great part of the cavity of the shell. It 

 is eaten when boiled, and has a flavour not unlike a lobster. 



Gen. I. CIDARIS. — Tubercles and spines connected by a 

 central ligament. The avenues of pores are parallel and 

 closely placed, rendering the smaller compartments narrow, 

 tortuous, and fit only for supporting small spines. The 

 plates of the larger compartments have an elevated tuber- 

 cle in the middle, with a groove round the base, surround- 

 ed with a broad smooth space, which is inclosed on the 

 margin of the plate, with a border of small tubercles, des- 

 titute of a pit in the summit. On each central tubercle 

 there is placed a large spine, connected by the central li- 

 gament and investing integument. M. Lamarck (Hist. 

 Vert. iii. 53.) considers this central ligament as a muscle 

 issuing from the interior, for moving the spine. But it has 

 no communication with the interior of the shell. He like- 

 wise supposes that the tubular suckers can be withdrawn 

 into the shell by the animal. But the division of the canal 

 at the base, for the passage of each branch through a dif- 

 ferent pore, renders this impossible. Round the base of 

 these large spines, smaller ones are placed, on the ring of 

 tubercles, which surround them like a sheath. Each avenue 

 consists only of a double row of pores, in pairs, correspond- 

 ing with a single row of tubular suckers. 



1. C. papillata. — Primary spines nearly cylindrical, with nu- 

 merous rough longitudinal ridges. 



C. p. major, Leske apud Klein, Ech. p. 125. tab. vii. A. and xxxix. — 

 2. Echinus Cidaris ? var. a. Sower. Br. Mus. tab. xliv — Found in deep 

 water, Zetland, where it is called the Piper. 



The body of the shell is about two inches in diameter, and depressed at 

 both ends. The longest primary spines are about four inches in length. The 

 shortest near the mouth do not exceed half an inch. These last are spatu- 

 late as well as the small ones on the oral plate. The plates of the division be- 



