166 PROF. F. J. BELL ON BIPALIUM KEWENSE. [Mar. 16, 



3. Note on Bipalium kewense, and the Generic Characters 

 of Land-Planarians. By Professor F. Jeffrey Bell, 

 M.A., Sec. R.M.S. 



[Eeceived March 16, 1886.] 

 (Plate XVIII.) 



In the descriptions given by writers on Land-Planarians especial 

 attention is always directed to the form of the head or, as more 

 than one author has called it, the tail. This, no doubt, is partly due 

 to the fact that in a number of the species the head is often seen to 

 have a remarkable hammer-shaped or cheese-knife form, which has 

 three times led to the institution of a genus for the reception of such 

 species. In other cases, where the worm has been assigned to other 

 genera, the head is described as obtusely rounded, or as not sharply 

 distinguished from the body. 



Having lately received from Mr. Osbert Salvin, F.R.S., a specimen 

 of a Land-Planariau (apparently Bipalium kewense, Moseley), found 

 by him among broken flower-pots in his garden in Sussex, of the 

 origin of which nothing definite is known, I have been enabled to 

 watch the creature exhibiting its activity. I had not long been study- 

 ing it when I noted that the head varied considerably and almost 

 constantly in form, so that I thought it well to at once enlist the 

 skilful pencil of Mr. C. Berjeau to represent its various appearances. 



Figure A represents the worm, not indeed at its greatest length, 

 but in a position which it is apt to assume when in full activity ; the 

 head is carried a little higher than the rest of the body, its edges are 

 sharp, its contour convex, and it is well marked off from the rest of 

 the body. Figure B, on the other hand, shows the animal in a state 

 of torpid quiescence ; the head is now contracted, obtusely pointed, 

 only separated by a shallow depression on either side from the sur- 

 rounding region of the body. Fig. C shows an intermediate condition 

 between A and B. Figs. D-G sliow various stages in the form of 

 the head^ — hammer-shaped, knob-like, tongue-shaped, or altogether 

 irregular. The body may be not more than 2 inches long, when 

 the creature looks like a leech or a slug, or it may extend itself to 

 6 inches and even more, when it has rather the appearance of a 

 thread-worm. In fact, as one looks at it extended on a white dish, 

 it calls to mind the Amoeba more than any other animal known to 

 the zoologist. 



I insist on the variations in the form of the body, and especially 

 of the head, because all writers (even those who, like M. Humbert, 

 Prof. Moseley, or, the latest of all. Dr. J. C. C. Loman, have had the 

 opportunity of examining these forms alive or under natural condi- 

 tions) direct, in their descriptions, especial attention to the form of 

 the head ; indeed, land-planarians with cheese-cutter or hammer- 

 shaped heads {cf. figs. A and D) have been by all naturalists 



' All the figures are of the natural size. 



