Protozoa and Rotifer a at Havana, III. 329 



50. A. radiata Zach. ('94). 



One example observed by Dr. Kofoid in plankton from the 

 river at E, in May. 



Subfamily Salpingcecin^:. 

 SALPINGCECA James-Clark. 



Loricated, solitary, attached directly or by pedicel. 



51. S. minuta Kent. 



This extremely small form was found attached to the 

 loricae of Dinobryon sertulari'a from the river, in May. 



Order DINOFLAGELLATA. 



Suborder DINIFEBA. 



Family PERIDINID-ffi. 



Peridinium Ehrbg. 



Free-swimming, covered with an ornamented shell en- 

 circled by an equatorial groove, dividing the shell into two 

 similar halves, the anterior formed of thirteen or fourteen 

 plates, the posterior of seven, two of which, nearest the pos- 

 terior extremity, are each often drawn out distally into a 

 horn-like prolongation. A moderately wide longitudinal 

 groove extends back from the equatorial groove at the middle 

 of the ventral surface. Two fiagella, one of which lies in the 

 equatorial groove. 



52. P. tabulatum Ehrbg. 



Found in July and August, but only in Thompson's and 

 Matanzas lakes, abundantly in the former situation though 

 not in any of the intervening waters. 



CERATIUM Schrank. 



Differing from Peridinium especially in the form and 

 structure of the shell. This is somewhat flattened dorso- 

 ventrally, with a broad uncovered area on the ventral surface ; 



