154 Transactions. — Zoology. 



Professor Huxley (Anat. of Invertebrate d Animals), on the authority of 

 M. Milne-Edwards, describes the spring and the piston-like body as re- 

 sembling the sponge of a gun with a spiral screw turned on the handle. I 

 have carefully endeavoured to confirm this observation so far as the species 

 under notice is concerned, but have not been able to do so. There seems 

 to be always a spirally coiled thread encased in a transparent tube or 

 sheath. The nearest approach to an axis bearing a screw is when the coils 

 are thrown close together, as often happens. I have added a sketch (fig. 7) 

 of a close portion of a coil, drawn from the J in. objective with the camera 

 lucida. 



Female. — The only female specimen I have been able to obtain is a very 

 small one (about 2 inch, in length) and much mutilated. The organs I have 

 been able to observe are the long, narrow, nidamental glands, lying on the 

 median line just above the gills, the oval flat and apparently stalked acces- 

 sory glands immediately below them, and the ovary. The ovary in this 

 specimen is very small and is somewhat pyramidal in shape, the apex lying 

 at the upper end of the body. I am not sure that I have correctly observed 

 the oviduct, but what I take to be the oviduct opens on the left side, having 

 passed, under the branchial heart. 



(Note. — The fact that this specimen is the only female among ten that I 

 have examined, and that the males were all fully ready for congress, would 

 seem to show that sexual selection may have considerable scope among 

 the members of this species.) 



Alimentary System, (pi. vii.) 



Mandibles (fig. 2). — Within the annular inner lip already noticed, are two 

 vertical conchiolin jaws forming the beak, the posterior jaw overlapping the 

 anterior one. The exposed parts are reddish-brown in colour, while the 

 covered parts are transparent and colourless. Each jaw consists of an 

 uncus, ala3 and apophysis, the alae being backward and lateral expansions 

 of the uncus. 



In the anterior or upper-jaw the uncus runs forward in a decurved line, 

 terminating in a sharp point. The outer border of the alas forms a con- 

 tinuous curve with this line, and runs backward to about half the length of 

 the apophysis, from which it stands out prominently. The lower border of 

 the alee is a concave curve ; and the front border, from the margin of the 

 uncus, presents a waved outline. The apophysis extends downwards, its 

 greatest length being at its outer margin. It is fully twice the size of uncus 

 and alffi. Its inner border forms a convex curve, which extends round to 

 the under -border, where it becomes concave. 



In the posterior or under -jaw the uncus is not so large as that of the 

 upper -jaw, is more obtuse, and is proportionately stouter. The alae extend 



