Mr. P. H. Gosse on the British Rotifera. 197 



which, unaware of its publication five years previously, he recog- 

 nised and defined under another appellation. 



In order to illustrate this memoir more perfectly, I forward 

 outline figures of the two species, a step which will doubtless 

 meet with the approbation of the discoverer (now resident in a 

 distant colony), who evidently intended the publication of his 

 own original and beautiful drawings. 



Dublin, July 1851. 



P.S. — Dr. Pfeiffer writes, from London, that a perfect speci- 

 men of Pterocyclos biciliatus is to be seen in a collection there, 

 and that the true Cyclostoma planorbulum of Lamarck (Encycl. 

 Meth.) must be referred to Pterocyclos, as well as C. tenuilabia- 

 tum 3 lately described by Mr. Metcalfe, from Borneo. Dr. Pfeiffer 

 has failed, equally with myself, in procuring an examination of C. 

 spiracellum, Adams and Reeve, which is not to be found in any 

 London collection. 



15th August, 1851. 



EXPLANATION OF PLATE V. 



Fig. 1. Pterocyclos Blandi. 

 Fig. 2. Troscheli*. 



XVIII. — A Catalogue of Hotifera, found in Britain ; with descrip- 

 tions of five new Genera and thirty-two new Species. By 

 Philip Henry Gosse, A.L.S. 



The following catalogue contains the species of the class Roti- 

 fera that have occurred to my observations within the last three 

 years, for the most part in the immediate vicinity of London, 

 and all in fresh water where not otherwise stated. I have ar- 

 ranged them on the system of Professor Ehrenberg ; not that I 

 think his classification natural, but because none more conve- 

 nient has been published. I hope soon to be able to give to the 

 world an arrangement of this interesting group constructed more 

 according to the organization and the natural affinities of its 

 members. This list of species, however, needs not be delayed 

 until that system be perfected. 



Of the species here enumerated, one hundred and eight in 

 number, seventy-one are found in Prof. Ehrenberg's ' Die Infu- 



* Figures of the following species will be found in the Nuremberg 

 2nd edition of Chemnitz, vol. Cyclostomacea : — 



P. rupestris, pi. 24. f. 21-5. P. anguliferus, pi. 24. f. 3-6. 



— var. minor, pi. 31. f. 9-11. — bilabiatus, pi. 24. f. 11-14. 



— hispidus, pi. 24. f. 7-10. — Albersi, pi. 28. f. 1-5. 



— parvus, pi. 31. f. 12-14. — Cumingi, pi. 31. f. 6-8. 



