24 Mr. P. H. Gosse on Asplanctna priodonta. 



ovary. To avoid confusion, the tortuous threads, with the tre- 

 mulous tags and the muscles, shown, are those of one side only. 



b. Female : vertical aspect of the head. The upper side is the occiput, 



where are seen the two incmved lobes, the small antenna;, and 

 (more forward) the lateral eyes. In front are the two conical 

 masses, and between them, but on a lower level, the forceps- like 

 jaws, with their cushion, pointing towards the pharyngeal tube, 

 which is furnished with an eye near its margin. 



c. The jaws, seen vertically, under pressure. The delicate serratures on 



the edges, the two termmal points, and the accessory uncini are 

 shovvTi. 



d. The jaws seen laterally. The serratures are cut in the t/pper edge, which 



seems to project inwardly. The terminal points are unequal, the 

 upper being the longer. The uncini are attached to the lower 

 edge. 



e. Male : dorsal aspect. 



/. Idem : lateral aspect ; right side. The globular organ near the lower 

 part is the sperm-sac, with a short bifid penis below it ; the pre- 

 putial sheath opens near the pointed extremity of the body. 

 Above the sperm-sac a granulated organ is seen extending from 

 it to the front of the head. Muscular threads, both longitudinal 

 and transverse, are seen, as is also one of the tortuous glands, like 

 a thickened cord. The phaiyngeal eye and one lateral eye are 

 represented. 



Plate II. 



h. Female : left side. The head is retracted ; the crop is corrugated in its 

 ordinary condition of repose : the bladder is distended : there is a 

 developing ovum in the ovisac, M'hich has several conspicuous oil- 

 globules. One of the dorsal and one of the ventral orifices are 

 well seen. Some of the organs represented in a. are not repeated 

 here. 



i. Female : dorsal aspect. The head expanded ; the cilia rotating ; the 

 pharjngeal tube, with its eye, the jaws lying on their cushion, and 

 the crop beneath, are seen ; below which is the long, tubular, very 

 expansible stomach, with its two pancreatic glands, terminating 

 in a wide sacculate portion. (Perhaps the latter might be pro- 

 perly considered as an intestine.) On each side is the tortuous 

 gland, and the developing ovum is showTi below all. The powerful 

 muscular bands that retract the head, the subordinate muscular 

 threads, and the transverse threads are well seen ; as are the ex- 

 tremely delicate floating filaments of nervous (?) matter, with their 

 numerous ganglia. 



P.S. Since the above was written, I had the pleasure of finding, 

 on the 30th of May, A. Brightwellii very numerous in several of 

 the little pools on Hampstead Heath. Volvox globator, Dino- 

 charis tetractis, Anuraa serrulata, and other interesting forms 

 were found wdth them. The females of the Asplanclma were 

 much more numerous than the males, perhaps in the ratio of a 

 hundred to one. I gladly bear testimony to the accuracy of 

 Mr. Dalrymple's anatomical figures of this species. — P. H. G. 



