166 



LOWER INVERTEBRATES. 



Ecliinothuridae. Cidaris metularia occurs in the Pacific and East India oceans, C. 

 thouarsii on tlie west coast of North America, and C. tribuloides on both coasts of 

 the Atlantic. Fine specimens of the latter measure five inches across the spines. 

 Dorocidaris papillata occurs at depths of from one hundred to six hundred fathoms, and 

 has extremely long fluted spines, so that an examj)le with a test about an inch across 

 will measure eight or nine inches from tip to lip of spines. It occurs in the Mediter- 

 ranean, and the Atlantic, while examples collected at the Philippines cannot be dis- 

 tinguished from it. I), hracteata, a Pacific species, has the flutes of the spines set with 

 serrations. 



In the species of Fhi/Uacaiithas the sjiines are often ornamented with frill-like 

 lamellaj, but vary greatly in shape and decoration. P. gigantea, of the Sandwich 



Islands, has ten 

 spines in a series, 

 and six or eight 

 lamelkv on each 

 spine. Gonioci- 

 daris canalicula- 

 ta is a species with 

 elegant spines, 

 toleral)ly abun- 

 dant in tlie south- 

 ern ocean. It has 

 been dredged in 

 .sixteen hundred 

 fathoms. In this 

 species the ujiper 

 ]iart of the test is 

 <(uite fiat, and the 

 two first series of 

 spines, which are 

 much larger than 

 the spines of Vid- 

 aris usually are on 

 that part of the 

 test, lean over to- 

 wards the anal 

 opening, and form 



an open tent for the protection of the young. These spines are cylindrical and 

 nearly smooth, the outer series longer and shorter than the inner. A somewhat 

 similar ari-angement obtains in Cidaris 7iutrix. Sometimes the young creep out, 

 with the aid of their first few pairs of suckers, upon the long spines of the mother, 

 and return to the marsuj)ium. 



Porocidaria purimrata has several rows of peculiar padille-sha]ied spines round the 

 mouth. These sjunes are flattened, longitudinally grooved, and serrated upon the edges. 

 Goniocidaris florigera is remarkable for the shaj^e of the primary spines set around 

 the anal area. These sj)ines are dilated at the tip in such a manner as frequently to 

 form a flattened cap, equalling in width one-third the diameter of the test. The oldest 

 species of Cidaris occur in the Trias, and are small forms with smooth tubercles. 



Fig. 145. — Cidar 



