44 NEOLAMPAS EOSTELLATA. 



Encope Michelini Agass. 



Yucatan Bank. 14 fathoms. 



Echinoneus semilunaris Lamk. 



Cuba. Littoral to 80 fathoms. 



Neolampas rostellata A. Ag. 



Florida Bank. 229 fathoms. 



PI XXII. 



A number of specimens of this interesting genus, of all stages of growth, 

 having been collected by the Blake in the Straits of Florida, I am able to 

 add considerably to our previous knowledge of the genus. As in all Cas- 

 siduloids. the affinities of the family to the Clypeastroids is more or less 

 marked. In the young specimens from Florida the changes taking place 

 in the actinostome, in the ambulacral system, and in the shape of the test, 

 as well as the structure of the pedicellarise and of the abactinal system, all 

 show strikingly the close affinities of the family with the Clypeastroids. 



In the youngest stage examined, measuring onty 2.5 mm. in length, the 

 test, instead of being globular, as is the case in the Spatangoids proper, is 

 quite flattened, its outline is elliptical, the anal system is covered by i'ew 

 large plates, and the general aspect of the young Neolampas at this stage 

 and in the following one, when it measures about 4.5 mm. in length, closely 

 resembles the young of some of the true Clypeastroids which 1 have had 

 occasion to examine, such as Echinocyamus, Mellita, or Echinarachnius. 



On their first appearance the bourrelets and phyllodes are with difficulty 

 made out, and in the earliest stages the actinostome shows no trace what- 

 ever of them. The ambulacral suckers are, like those of the Clypeastroids, 

 provided with powerful suckers near the actinostome, which are but slightly 

 developed above the ambitus; we find no fimbriated aetinal tentacles, even 

 in the largest specimens collected, measuring 12 mm. in length, so character- 

 istic of the Spatangoids proper. The bourrelets are well developed in speci- 

 mens of 10 mm. in length, and in the largest specimen ( 12 mm. long) they 

 have become very prominent The lateral crowding of the ambulacral plates 

 near the actinostome to form the phyllodes is well shown on comparing 

 the arrangemenl and size of the plates as seen from the interior of the test 



