Mr. P. H. Gosse on Asplanchna priodonta. 21 



Close to each plexus there is a minute orifice in the skin set 

 round with short setae, and a similar one is placed on each side 

 of the back, but a little higher up. From each of these four 

 apertures a thread floating freely in the cavity of the body goes 

 towards the head, having at its contact with the aperture a 

 thickened club-shaped ganglion or gland. 



The muscles are very numerous, and exert a powerful action, 

 especially in the syringe-like retraction of the head. The principal 

 pair are broad ribbons extending down each side from the head to 

 near the bottom of the body (see figs. a8ci). Another similar pair 

 run down one on each side of the back. The other longitudinal 

 muscles are chiefl}^ threads, sometimes forked at their insertions. 

 Very fine threads also keep the viscera in their places : thus two 

 are attached to the fundus of the stomach, tying it to the bottom 

 of the body. The ovary is attached to these and also to a dia- 

 gonal thread branching from one of the longitudinal pairs. At 

 the lower part of the back are two transverse muscles, which do 

 not extend round the body ; their contractions frequently draw 

 in the skin of this part in strong angular folds. All the cuti- 

 cular insertions are in a skin separable from the outer integu- 

 ment. Across the body, near the upper part or middle of the 

 back, go three parallel transverse threads, of which the upper- 

 most has each extremity prolonged in two branches ; viewed late- 

 rally (as in fig. a) they are often seen quite bowed, and appear 

 perfectly free, except at their insertions into the skin. They 

 often seem to connect one pair of longitudinal muscles, but are, 

 as I believe, independent. 



The coronet of thickened masses that surround the head is 

 probably muscular, bearing the cilia. Just below this there is a 

 series of five or six annular threads set in the inner skin, which 

 are probably muscular and aid in the complex movements of the 

 head. The reniform cushion that bears the jaws is doubtless 

 composed of powerful muscles ; and the delicate stomach with its 

 tube, the great crop and the ovisac, are covered with muscular 

 network. 



As a nervous system, each of the three eyes rests on a mass 

 that appears ganglionic ; the clubbed masses at the lateral aper- 

 tures are probably of the same character ; and the interior of the 

 body contains a number of very delicate threads floating freely 

 in the contained fluid, which have thickened knobs here and 

 there, especially where they anastomose (see fig. i). 



Such is the anatomy of the female. But the observations of 

 Mr. Brightwell and Mr. Dalrymple had taught me to look for a 

 distinct male, which I accordingly searched for. Many indivi- 

 duals I examined, but "all were females ; at length I found a small 



