314 ECHINANTHUS ROSACEUS. 



structure of the tubercles in the median ambulacra! space. When we ex- 

 amine the suckers coming from these pores, we find them totally unlike 

 those of the adult Echinanthus {PI. XT. /'. 17, 18). They are in every par- 

 ticular similar to those of the regular Echini, short, with a prominent well- 

 marked sucker, as seen in PI. XP. f. .', which represents a portion of the 

 petaloid rosette, while the character of the gill-like suckers of the rosette 

 of the adult is seen in PL XP. f. 17. Each primary sucker is surrounded in 

 the adult by small slender suckers, not differing from those found in young. 

 The long sucker is lobed on both sides lor half its outer length, and is pointed 

 (PI. XP. f. 18). The pores, discovered by .Midler in Clypeaster over the 

 whole surface of the test, are already well developed in young specimens 

 ( /'/. XP. ./'. 16 represents a part of an ambulacra! plate of the specimen 

 figured in PI. XP. f. l',\. These pores in young specimens carry regular 

 tentacles with suckers, as i- shown in /'/. XP./. • /. representing the c(]ge of 

 the test of the young specimen ( /'/. XP. f. /) crowded with anilnilacral 

 suckers and pedicellarise. The interna! structure of Echinanthus is early 

 developed (PI. XP. f. 15), specimens of the size of PI. XIII. f. 9 have 

 already the commencement of the double floor on the vt\^' of the test, 

 and the pillars which separate the ambulacral system from the digestive 

 cavity arise from the floor in sharp, numerous pillars. The changes the 

 interior passes through correspond to those which Encope goes through, 

 where the ambulacra in young stages are not isolated, resembling at one 

 time those of Mellita, but afterwards the cellular structure of Encope com- 

 pletely isolates them; in Echinanthus the double partition early makes its 

 appearance, though for a time the ambulacra are connected with the diges- 

 tive cavity, resembling the permanent condition of Clypeaster proper; but 

 at no time do we find in Echinanthus the peculiar arrangement of the am- 

 bulacral pores of the lower side in the sutures of the plates so prominent 

 and striking a feature of Echinocyamus (PI. Xlll.f. .', 3) and of Clypeaster 

 proper (PI XP./. 25). 



Numerous pigment cells, specially closely packed in the abactinal part of 

 the median interambulacra! space, indicate the commencement of the bril- 

 liant reddish-brown coloration so well developed in the adult. 



