Tripneustes esculentus (Leske). 



PI. II. Figs. 12, PI. VIII, Fig. 2. 



The development of this Echinoid was nol entirely unknown previously. 

 Tennent 1 ), who has used it for hybridization-experiments, has given 

 some sketches of the skeleton of the young larva in the age of relatively 

 24 hours and four days, and also a short description (under the name of 



Fig. 6. Skeleton of the young larva of Tripneustes esculentus; A. side view: R. front view, 

 from the ventral side; C. end view. 300 /i. Letters as in Fig.."). 



Hipponoc). It does not appear that Tennent has reared the larva to its 

 full size; at least he does not give any information about the later stages. 

 Artificial fertilization of this species was undertaken in March and 

 April 1916 at Tobago, B. W. I. The egg is small (I have omitted to note 

 the exact size), and not very clear. The cleavage is of the usual modus, 

 presenting no specially noteworthy features. Judging from Tennent's 

 observations the young Pluteus-stage may be reached already in the 



*) D. H. Tennent. Echinoderm Hybridization. Papers from the Marine Biological 

 Laboratory at Tortugas. Publ. No. 132 of the Carnegie Insl. Washington. 1910. p. 135. 

 PI. I. figs. 34. 



