215 



are pierced with holes, as in that species, for the passage of 

 water. 



The calcareous plates of the surface are less regulariy oval 

 than in S. tenuis, besides being relatively of smaller size. The 

 holes with which they are pierced are larger and are serrated 

 interiorly. The characteristic hooks (hamegons) attached to the 

 plates are similar to those of the species last mentioned, but the 

 external surface of the base is sometimes grooved. The breadth 

 of a plaie in a full grown specimen is about two twenty-fifths of 

 a millimetre. 



The genital tubes present a singular feature among Holothuri- 

 ans of this form, in being much branched, more than even in the 

 Thyonidia. A similar character has not yet been detected in 

 any other Synapta. In consequence of a lack of perfect spe- 

 cimens, the internal organs cannot be fully investigated. 



The twelve tentacula are longer and narrower than in S. tenuis, 

 with five to seven branches on each side. They contain multi- 

 tudes of exceedingly minute calcareous spiculse, each having 

 both extremities enlarged, with the enlarged portion in general 

 deeply furrowed. These spiculae differ strikingly in form from 

 those of »S. tenuis. The inner surface of each tentacle exhibits 

 commonly six of the little tubercles called by Quatrefages 

 Ventouses. 



This species is allied to S. inhcEvens and S. Duvernea of 

 Europe and to <S. tenuis of our own coast. It has little resem- 

 blance to »S'. Bachei or S. rotifera, its more immediate geo- 

 graphical neighbors. 



Mr. H. R. Storer read a medico-botanical paper on the 

 Magnolias. 



A number of shells were presented in the name of Mr. 

 Nathan P. Rice. The thanks of the Society were voted 

 for the donation. 



Seiior Juan Lembeye, of Cardenas, Cuba, and Rev. P. 

 Tocque were elected Corresponding Members. 



