278 THE AMERICAN MONTHLY [December, 



inner angles, narrowing towards the middle, then enlarging 

 slightly to the base of the tapering point, the contour of which is 

 slightly convex. This Rotifer is represented at Fig, 7. 



NoTOPS ci.Avui.ATus, Triphylus lacustris, and Philodina 



(species?). 



Bv G. WESTERN, F. R. M. S., 



L')ND(lN, ENGLAND. 



Notops clavulatus.— The general contour is that of the 

 female, even to the deep furrow at the posterior extremity, where 

 the large lateral muscles are attached, and the vase-like form when 

 the animal is seen from the ventral side is precisely similar; but 

 there is no sign of the foot, which in the female is so striking a 

 feature. From the total absence of the digestive organs the male 

 appears much more transparent, and the many muscles, which 

 are well developed in this species, are very apparent. I could 

 make out no vascular canals, vibratile tags, nor contractile vesicle, 

 though it is possible that the latter may be concealed in the mass 

 of viscera which stretches across the body cavity from front to 

 rear, the great bulk of which is made up of the sperm sac, inside 

 which the spermatozoa, large and very active, can easily be seen. 

 A large ganglion or brain carries an eye spot on its ventral side, 

 and the numerous nerve fibres may be traced from it to various- 

 parts of the body. This male (Fig. 10) I found in a gathering 

 from Richmond Park which Mr. Chapman has kept over three 

 weeks. Subsequently I succeeded in hatching it from small 

 white eggs which I had isolated for observation. From appar- 

 ently similar eggs I have seen females also produced, but possibly 

 further observation may enable us to distinguish the male from 

 the female egg. There is another kind of egg, much larger and 

 yellow in color, which is, I believe, the nesting egg. This I have 

 not yet succeeded in hatching. The average length of males I 

 measured was i-4oth inch. 



Triphylus lacustris. — The male o'f this Rotifer (Fig. 9) is a 

 reproduction in miniature of the form of the female, and it is from 

 this similarity in appearance and its association with the female 

 of the species that I have ventured to identify it, for I have not yet 

 been able to trace it fi'om the egg. The resemblance is not con- 

 fined to outward appearances, for its internal organs will also be 

 found to closely correspond with those of the female. The di- 

 gestive viscera, however, as is usual with male Rotifers, are 

 entirely wanting, and their space is occupied by the large sperm 

 sac. I caught just a glimpse of a large penis protruded behind 

 the foot. This male I found swimming amongst females in a rich 

 gathering I made at Chingford. The average length was 1-83 inch. 

 I may state that the females are very much larger than any I have 

 hitherto seen. 



