C. F. ROUSSELET OX LITTLE-KNOWN PTERODINA. 27 



lateral canals lie close to the intestine, and flame cells were seen 

 .along their course. The stomach and intestine were seen to be 

 filled mostly with diatoms. 



Size : length of lorica yi^ in. (204 /x), width ^^^ in. (136 fx). 

 The Male. Mr. Dixon-Nuttall has found the male of this 

 species, the first male Pterodina ever seen ; it is shown in 

 Fig. 4, e and /. In outline it is very narrow, elongated, and 

 quite unlike the female. It has a decided, but rather soft, lorica, 

 aiid two red eyes in front, but is devoid of jaws. The copulatory 

 organ projects dorsally above the foot, which is of usual structure 

 and ciliated at the end. Size about ^^ in. (127 /x). 



In a private letter Mr. Bilfinger states that he has observed 

 the male of Pt jxctina, which agrees with that of Pt. elliptica in 

 every particular. 



Pt. dyioeata (Plate 3, Fig. 2). This is a very old species, 

 first seen in the second half of last century (1786) in sea- water 

 of the Baltic by 0. F. MUller, and afterwards described by 

 Ehrenberg, who appears to have observed the thick rounded 

 edges of the lorica, but thought the edges were merely curled 

 round. Mr. Gosse's figure in the Rotifera (Plate XXVI., Fig. 14) 

 is scarcely accurate ; it is represented too square and too angular 

 posteriorly, and as being flat. I have obtained this animal from 

 ]Mr. John Hood, who, I believe, finds it occasionally in brackish 

 tide pools of the estuary of the Tay; and from these the 

 accompanying figures have been drawn, partly by Mr. Dixon- 

 Xuttall and partly by myself. 



The lorica is a long oval with a squarish look about it, which is 

 well expressed in the figure. It is of considerable thickness, 

 •convex dorsally, and has thick rounded edges with a smaller 

 convex ventral side, as will best be understood by the transverse 

 section, Fig. 2c. The anterior dorsal edge of the lorica is a smooth 

 rounded line, the mental edge is slightly wavy with a fairly deep 

 semicircular sulcus in the middle. The foot opening looks like a 

 mere slit in the ventral plate at some little distance from the 

 posterior edge. The lateral antennse are situated at the sides, a 

 little above the middle. Eyes of usual shape are present, and 

 the anatomy otherwise is normal ; Fig. Id is Mr. Nuttall's 

 drawing of the jaws. 



Size : length of lorica yy-y in. (150 />t), width ^riy in. (102 /x). 

 Pt, cceca (Plate 3, Fig. 1). This is another species found 



