Mr. P. H. Gosse on Asplanchua priodonta. 19 



and curving round nearly parallel with its extremity, forming a 

 sort of accessory tooth. The whole apparatus reminds us of the 

 maxillse of an insect with the maxillary palpi. The other obvious 

 distinctions are found in the form of the general outline, in that 

 of the stomach, in that of the ovarj^, in that of the tortuous glan- 

 dular threads (which Professor Ehrenberg calls seminal glands), 

 in the arrangement of the tremulous tags, and in the form and 

 size of the contractile bladder. 



The form is that of a membranous purse, most delicately 

 transparent, and therefore very difficult to detect with the naked 

 eye. It is almost regularly oval, the dorsal side however being 

 rather inclined to be the longer. The front is furnished with a 

 coronet of muscular masses, carrying cilia, which form two vor- 

 tices. The centre of the head, or space thus surrounded, rises 

 into two low conical protuberances, set rather forward, over which 

 several muscular threads ramify and cross each other : between 

 these, rather behind, is an oval opening, the entrance of the 

 pharynx, just within the margin of which on the hinder side is 

 placed a small eye of a rich crimson hue, as a guardian to the 

 passage. A ganglion supports it. Ou each side of the circum- 

 ference a ganghonic lobe projects, which carries another red eye 

 equally rich, but smaller. The eyes are beautifully distinct when 

 viewed by reflected sunlight. The hind head terminates in two 

 incurved thick processes, between which there is a rounded ex- 

 cision, and on each side of these curved lobes there is a little pro- 

 jection carrying a thick short seta. I feel little doubt that these 

 organs, of which either one or two are found in most of the 

 Rotifera, and which Ehrenberg calls respiratory tubes, are rudi- 

 mentary antennae. Threads with bifurcate extremities go from 

 the centre of the head to each cone-top, each lateral eye and each 

 antenna. Below the cones lies a kidney-shaped muscular cushion, 

 to one lobe of which is attached the jointed dental forceps, 

 pointing horizontally backwards, while the other and larger lobe 

 is spread beneath, probably as a rest to support the prey while 

 the teeth masticate and lacerate it. On the top of this cushion 

 are seen several yellow glandular (?) spots varying in number. 

 The mouth leads by a narrow oesophagus into a capacious mem- 

 branous crop, ordinarily of a somewhat cubical form and much 

 corrugated, but capable of great expansion, when its surface is 

 seen to be covered with a beautiful network of muscular threads, 

 with thickened points of interlacement. In PI. I. fig. a. it is 

 seen expanded, as when food is entei'ing ; in PI. II. fig. h. it is 

 in its ordinary state. I think that when the animal is cognizant 

 of food brought to the mouth by the ciliary vortices, it suddenly 

 expands the crop by the action of the muscles that go from it to 

 the skin, when the water rushing in to the vacuum carries in 



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