372 CHARLES F. ROUSSELET ON NOTHOLCA TRIARTHROIDES 



back, and has six fine longitudinal markings. The occipital edge 

 is armed with six spines ; the ventral plate is flat, and gapes 

 posteriorly. Size of lorica, exclusive of spine, ^^-^ in. (212 /x). 



Cathypna brachydactyla Stenroos (Plate 13, fig. 3). 



This rare species was first figured and described by Stenroos * 

 in 1898 from Finland, but does not appear to have been re- 

 corded since. Kecently I found a few specimens in material 

 collected by E,. Lucks in a pond in the Ottominer Marsh near 

 Danzig, which enables me to extend, and in some respect correct, 

 Stenroos's description of this somewhat peculiar little Cathypna. 



As will be seen by the figure (Plate 13, Fig. 3) drawn by 

 Mr. A. R,. Hammond, the hyaline lorica is broad and oval in shape, 

 but flat and compressed dorso-ventrally, with but a slight con- 

 vexity dorsally, as shown in the longitudinal and transverse 

 sections, Figs. 3a, 3b. 



The dorsal plate is less wide and considerably shorter than 

 the ventral plate, terminating posteriorly in a straight line just 

 over the foot opening. Anteriorly this plate has a wide, straight, 

 and slightly undulate margin, with sharp points on either side, 

 which are clearly seen when the animal is contracted, con- 

 trary to Stenroos's description. 



The ventral plate is more deeply excavated anteriorly, and 

 posteriorly terminates in a fairly wide, short and flat appendage, 

 which is cut off nearly straight, with a very slight curve inward ; 

 it extends some little distance beyond the foot-opening. The two 

 plates of the lorica are connected with a flexible membrane on 

 both sides and also posteriorly, and the line of inangulation can 

 readily be traced all round. Stenroos does not mention these 

 details, but they are clearly indicated in his figure. 



The foot-opening is situated on the under side of the flat ventral 

 plate, some little distance from the posterior margin. The foot 

 consists of a single, short, square joint, and carries two very 

 short stiletto-shaped, acutely pointed toes, which project only 

 with their points beyond the posterior appendage ; the toes are 

 cylindrical, not flat blades. 



Stenroos further states that in life this Rotifer projects its 



* " Das Thierleben im Nurraijarvi-See," Acta Societatis iiro Fauna ct 

 Flora Fennica, xvii. 189S, p. IfJO. 



