324 ENCOPE. 



(PL XL f. 13). The posterior ambulacra] hmules (notches) are the first to he 

 developed, the young Mellita having at this stage (excluding the posterior 

 interambulacral lunule) somewhat the shape of a diminutive Echinodiscus, 

 or Encope Michelini, and as the cuts increase in depth with advancing age(P/. 

 XI. f. 19) resemble in a remarkable degree a small Encope grandis. The 

 commencement of the closing process of the notches is shown in drawings of 

 M. longifissa (PL XI. f. .;, .'7), while in/. 26, 27, of the same Plate, the 

 lunnles are completely closed. 



The large series collected by the Thayer Expedition along the whole coast 

 of Brazil shows that this species has a wide geographical range, and is liable 

 to great variations, indicating that tin' characters which have been described 

 as separating M. quinquefora and M. testudinata have no permanent value. 



Littoral to 7 fathoms. 



KXCOPE. 



Encope A.GAB8. 1840. Cat. Syst. Ectyp. 



Contains species of considerable size ; actinal surface flat, abactinal more 

 or less regularly arched ; always having in the prolongation of the ambu- 

 lacral petals cither lunules or indentations, which \ar\ extremely according 

 to age. and in different individuals of the same species. There are live geni- 

 tal openings, while there are only four In .Mellita. The ambulacral petals are 

 very unequal in size, the posterior pair usually larger than the anterior ones. 

 Ambulacral furrows greatly ramified. The main difference between this 

 genus ami .Mellita consists in the continuous calcareous partition which 

 separates the buccal from the digestive cavity, in place of the disconnected 

 pillars of Mellita. Outline elliptical, truncated posteriorly. In addition, we 

 have in Encope a horizontal floor separating the buccal cavity front the 

 upper part of the test, in which the ambulacral system is confined, while 

 in Mellita the ambulacra! petals open directly into the main cavity above 

 the buccal orifice. 



