344 Transactions of the Society. 



In Bolivia. 

 Additions to the list already published {49). 



Cathypna liornemanni Ehr. Lake Titicaca. 

 *G. nana sp. n. Lake Titicaca. 

 Monostyla closterocerca Schm. Lake Titicaca. 



In Bkitish Guiana. 



Additions to list already published (4-^). 



*Monostyla asymmetrica sp. n. M. cochlearis sp.n. 



Genus Cathypna Gosse (^^). 



In this paper I include all the species of Cathypnidse hitherto 

 described under the names Cathypna and Distyla in the one genus 

 Cathypna. I do not profess the authority necessary to assume 

 that in doing so I reach finality according to the rules laid 

 down by priorists, but I may state my reasons for the change. 



I can see no structural distinctions of generic value between 

 the animals called Distyla and those called Cathypna. They are 

 structurally identical. Tht slight difference in relative length and 

 breadth, of which much has been made, is not a generic character, 

 and has been usually quite forgotten when new species have been 

 described. If the two genera were retained the species would have 

 to be redistributed in order to show some regard to the assumed 

 generic characters. 



As both cannot be retained, all the species must go into one. 

 The two names are of nearly equal age and standing. Distyla is 

 the earlier, but the name was used long ago for a Eotifer of 

 another family {D. weissei Eichwald 38). Cathypna has not, so far 

 as I am aware, any stain of this sort on its character, and so it 

 seems to me a suitable name for these animals. 



All the animals were drawn on a uniform scale, which was 

 then reduced by photography for reproduction in the plates, to a 

 magnification of 260 diam. 



Cathypna grandis sp. n. Plate XIII, figs. 20a, 20h. 



Specific Characters. — Very large, oblong; dorsal plate slightly 

 broader, truncate behind ; anterior margins nearly straight and 

 nearly coincident ; lateral sulcus very deep. Segment after dorsal 

 plate broad, bearing triangular pointed prominences on each side 

 of the foot. Toes scarcely half the length of dorsal plate, with 

 prominent shoulder on outer side and claw. 



Description. — Length of contracted lorica about 200 /x, of dorsal 

 plate 180 yLt, width of dorsal plate 160 yit, of anterior margins about 



