C. F. ROUSSELET ON DIPLOIS TRIGONA. 121 



After careful consideration I have come to the conclusion that 

 Gunson Thorpe's Rhinops orbiculodiscus * and Bergendal's Micro- 

 codides dubius t are one and the same species. Unfortunately 

 Surgeon Gunson Thorpe has made some errors in the description 

 and figure of his species, some of which he has already corrected 

 himself. I have often seen this animal of late, and can affirm that 

 it resembles M. dubiusmwth more closely than the published figure 

 shows. My animals were identified by Surgeon Gunson Thorpe 

 himself, to whom I sent a mounted slide on board his ship, cruising 

 in Australian waters. The following are the points requiring 

 correction in Gunson Thorpe's description : — First, Rhinops orbi- 

 culodiscus has a red cervical eye ; secondly, the corona consists of 

 a closed outer ciliary wreath, having a second wreath within it, 

 leading to the mouth, which is situated in a depression a little 

 below the centre of the Corona, as fairly well indicated by Bergen- 

 dal's diagrammatic figure 11; thirdly, it has only one toe ; the 

 second toe-like structure is smaller, nearly always carried at right 

 angles to the toe, and better termed a spur ; fourthly, the lateral 

 antennse do not issue from the tip of the projecting lateral points 

 in the lumbar regions of the body, but in the angle between these 

 and the body ; fifthly, the animal is not a Rhinops. These 

 corrections in the description of R. orbiculodiscus practically effect 

 a complete agreement with M. dubius. Adopting Bergendal's 

 generic name the correct designation of this animal will therefore 

 be Microcodides orbiculodiscus, and I have placed a mounted slide 

 of it in the cabinet of the Club for reference. 



Microcodides rolustus (Glascott), PI. VI., Fig. 1. 



In her list of some of the Rotifera of Ireland (] 892) Miss L. 

 S. Glascott has described, under the name of Microcodon robustus, a 

 new one-toed Rotifer, which, unfortunately, cannot be identified 

 from her figures ; the description of the animal, however, is much 

 better, and by it I have been able to identify it with a Rotifer I 

 have found in water received in December last from Mr. F. 

 Daunou, of Margate, from his garden tub. I am, therefore, 

 enabled to give a good figure of this pretty Rotifer, which had a 

 few months previously been seen also in Germany by Mr. L. 

 Bilfinger, of Stuttgart. 



* " Journal Koyal. Micr., Soc," 1891, p. 304. 



t "Zur Rotatorien Fauna Gronlands," pp. 34-43, 1892. 



