166 MR JAMES MURRAY ON 



Family Pi/esomad^e. 



Plaesoma truncatum (?) Levander (29). Frequent. Ploesoma triacanthum(1) Bergendal (3). Lochs Oich 



,, hudsoni, Imhof. Frequent in N. Uist. and Uanagan. 



Family Gastropodid^e. 



Qastropus dylifer, Imhof (23). Common, noted in about 70 lochs. 



Family Anapodid^e. 



Anapus testudo, Lauterborn (28). Lochs Ness, Huna, and Uanagan. 



Notes on some of the Species, and Descriptions of New Species. 



Melicertad^e. 



Melicerta. — Empty houses of species of this genus were found adhering to plants in 

 Lochs Ness and Ruthven, but no living example was seen. 



Pseudcecistes rotifer, Stenroos ? (Plate V. fig. 18) (48), a gigantic free-swimming 

 Rhizotan found in the shallow water of Inchnacardoch Bay, Loch Ness, is doubtfully 

 referred to this species by Rousselet, who has only seen my rough sketch of it. It 

 has much resemblance to G^cistes velatus, Gosse, but is much larger, and has the eyes 

 quite differently situated. 



Mr Rousselet informs me that Dr Collins figured and described a form having 

 the eyes near the edge of the corona, and has himself collected such an animal in 

 Dr Collins's favourite pool near Sandhurst. He adds that the eyes are seated on an 

 elevated cushion, a feature shown in my sketch. Our animals were larger than any 

 which Stenroos measured. Total length, 925 n (Stenroos, 750 m) ; length of trunk, 450 m 

 (Stenroos, 280 m) ; diameter of corona, 295 m (Stenroos, 220 m). Our measurements were 

 made from free examples, Stenroos's from sessile individuals, and the trunk is therefore 

 more extended and narrower relatively in ours ; the measurement of the corona is less 

 in excess of his. 



My drawing may be taken as a faithful representation of the general form and 

 proportions, and of the viscera as far as shown. The details of the head were less 

 successfully observed, and I failed to make out the correct orientation of the parts. 

 For these, Stenroos's figure (48) may be consulted. The antennae were not detected. 



Stenroos figures the eyes within the corona ; my drawing shows them outside the 

 principal wreath. As Stenroos expressly says that the eyes are deep-seated, the 

 difference may be optical, and due to the point of view. Rousselet says the eyes are 

 on the ventral side. 



A very powerful, rapid swimmer, as it rushes across the field with the immense 

 hyaline corona widely expanded, it is one of the most magnificent of Rotifers. 



