Australasian Rotifera. By J. Murray. 457 



double. The processes are extremely thin, like knife-blades, and 

 closely appressed to one another. Stenroos shows this process as 

 terminating the body, whereas I see an apparent segment posterior 

 to that from which the toes spring. 



In both dorsal and ventral views the toes appear to be widely 

 separated, springing quite laterally from the segment bearing them. 



The toes are quite equal, while Stenroos says they are unequal. 



1 have not seen the animal alive. The contracted specimens 

 have the toes curved forward till their tips are nearly on a level 

 with the front of the lorica. 



Rattidus orca sp. n. Plate XIX, figs. 10a, 10&. 



Specific Characters. — Lorica and toe of about equal length ; 

 lorica narrow, elongate, having a prominent ridge on the anterior 

 half, the ridge with a large procurved spine. Substyles short and 

 subequal. 



Dcscri-ption. — Length of extended lorica, excluding the head, 

 150 yLt, of contracted lorica 140 /a, of toe 160 /x, of substyles 10 /x. 



The figures explain the form best. The specimens were deeply 

 coloured by osmic acid, so I have not any details of the internal 

 structure. I never saw the live animal. The toe is not bent at 

 an angle to the body, but follows its median line. The hyaline 

 ridge covers rather more than the anterior half of the body. 

 The spine varies in size, and is sometimes more prominent than in 

 the examples figured. 



The resemblance of the dorsal " fin " to that of the Killer 

 Whale {Orca gladiator) suggested the specific name. Of course, 

 it differs in being procurved instead of recurved. 



Hcibitat. — Pond in moraines of Miiller Glacier, New Zealand ; 

 some dozens of specimens. 



The dorsal spine distinguishes the species from all others. 



Monostyla sp. (undescribed). Plate XIX, figs. Za-oh). 

 (Discovered, and to be described, by Mr. Harring.) 



Description. — Large, oval ; dorsal plate broader, truncate at 

 both ends. Anterior dorsal margin nearly straight, ventral deeply 

 excavated, the middle part being a flat V with the bottom rounded. 

 Lateral sulcus moderately deep. Posterior lobe of lorica not very 

 prominent, rounded. Toe long, with nearly parallel sides, with 

 rounded shoulders and short claw. 



Length of contracted lorica 130 yu,, of dorsal plate 120 /x, of 

 toe 85 //-, of claw 8 /x ; breadth of dorsal plate 90 /x, of ventral 

 plate 80 yLt, of anterior margin 60 fjb. 



Closely related to M. Innaris, of which I thought it might be a 



