J. HOOD ON THREE NEW ROTIFERS. 283 



ephippial eggs being carried singly, and male eggs in clusters 

 of four to six, but I have not yet been able to see the male. 



A dorsal antenna, consisting of a small pit furnished with 

 stilf setae, is situated low down near the centre of the dorsal 

 side ; the lateral antennae could not be found in the posterio- 

 lateral angles, and in both these particulars the animal differs 

 from P. platyptera. 



A fairly large contractile vesicle is obvious in the posterior 

 part of the body cavity. I first found a few examples of P. 

 aptera in the spring of 1892 in water from Loch Lintrathen, 

 Forfarshire, and again in large numbers in March of this year, 

 associated with Synchceta longipes, 8, tremula^ Folyarthra 

 platyptera^ Notops pygmceus, GonocJiilus unicornis^ Amtrcpa aculeata, 

 cochlearis and hrevispina, Notholca lo7igispina, and very few 

 examples of the very peculiar Rotifer lately described by 

 Wierzejski and Zacharias under the name of Bipalpus 

 vesiculosus. Size of female -^—q to 2 J^in. Habitat : Lakes in 

 Scotland. 



BracMonus tridens, n. sp., PL XII., Fig. 3. 



Specific Characters. — Occipital spines three, lorica thin, 

 smooth, transparent as in B. pala. Posterior spines absent. 

 Marine. 



The chief peculiarity of this new marine Brachionus consists 

 in having only three spines on the occipital edge of the lorica, 

 one of which is median. In other respects the lorica resembles 

 that of B. pala, but without posterior spines. 



I found this Rotifer sparingly already in 1885 in the Tay, 

 associated with B. Mulleri, Pterodina alypeata, Notholca thalassia, 

 Golurus dicentrus, Mytilia tavina, and have never met with more 

 than five or six specimens. The corona is more like that of 

 B. lorceolaris, but in all other respects the anatomy resembles 

 that of B. pala. Foot long and wrinkled. Size of lorica ^V^* 

 Habitat : Salt and brackish water. Scotland. 



Explanation of Plate XII. 



1. Floscularia spinata. 



2. Polyarthra aptera. Dorsal side. 

 2a. Ditto. Contracted shape. 

 2&. Ditto. Jaws. 



3. Brachionus tridens. 



4. Eattulus hicornis. Jaws* 



