Protozoa and Rotifera at Havana, III. 367 



27. P. platyptera Ehrbg. 



This is one of the four species that were present during 

 every month of the year. It seems to thrive best in cold 

 water, for it was most abundant during December, January, 

 and March, and reached its minimum in June. It was found 

 in all the bodies of water under observation. Many indi- 

 viduals were larger than the dimensions given by Hudson and 

 Gosse, some of them measuring .2 mm. in length. Rhabdo- 

 styla was found parasitic on many that were taken in Phelps 

 Lake. 



28. P. platyptera euryptera Wierz. ('91). 



Rare ; found in September, in towings from the Illinois 

 River. 



29. P. aptera Hood ('93). 



In November, 1894, a quantity of dried mud from the 

 bottom of Phelps Lake was taken to the University, and, as 

 has been previously stated, aquaria were started by putting 

 filtered water upon this mud. This species was found at two 

 different times in these aquaria, but was not observed at any 

 of the substations. 



TltlARTHRA Ehrbg. 



Body sac-like ; spines single, two lateral, one ventral ; eyes 

 two, frontal ; mastax of moderate size ; tropin malleo-ramate. 



30. T. longiseta Ehrbg. 



Not especially common but generally present in both years 

 in the river and lakes studied except Flag Lake, during the 

 period from April to September. A very few were also seen 

 in both years in December and February. 



Plate ('85) describes a new rotifer, calling it T. term 'mails. 

 He says: "The attachment of the posterior spine is not 

 ventral but terminal, just in front of the anal opening, and 

 the spine cannot be flexed anteriorly. The spines are smooth, 

 although I found one individual in which they bore very small 

 spinules, as in T. longiseta." 



Many of the individuals taken here had smooth spines, 

 while others had them notched. The posterior spine was 



