74 rn.f. M'liitosl.'s Notes from the 



3. On Bifid A^cmericans (Cercbratulus anj]julatns, O. F. I\I., 

 = marginatum, Renter?) from Aberdeen and Naples. 



The occurrence of a bifid Ncmertean is by no means 

 common; indeed, during the examination of many hundreds 

 in various groups such a condition was unknown. It was, 

 therefore, witli niucli interest that au cxamidcof Cerchratvlus 

 aiH/ulattis (PI. III. tig. 1) with a bifid tail was receiA'cd early 

 in' 1901 from Dr. Charles II. "Williamson, M.A., of the 

 scientific staff of the Fishery Board for Scotland. Tiic 

 specimen was obtained by a liner attached to a hook iu 

 Al)erdeen Bay in November 1903, and it is noteworthy that 

 all those captured in St. Andrews Bay liad been hooked 

 when feeding on the mussels used as bait. One exception 

 only need be alluded to, viz. the case of a very large exam})lo 

 which, in a contracted state at the surface, on a warm and 

 calm morning, resembled a sole. The fisherman stretched 

 out his hand-net to capture it, and instantly, to his astonish- 

 ment, it shot out more than a yard in length. When brought 

 to the Laboratory it, like its predecessors, swam swiftly and 

 gracefully through the water, with an undulatory motion — 

 from above downwards — ^just as an eel docs laterally. This 

 pelagic habit has also been noticed in foreign representatives 

 of the genus. Thus the late talented young zoologist 

 Mr. F. P. Bedford, whose early death was a great loss to 

 science, caught various examples of Cercbratulus natans, 

 II. C. Punnetf^, swimming in shallow water at night, and 

 observed them near the bottom by day. The bifid tail \\\ 

 the piesent case would certainly, at any rate, not interfci'e 

 with this natatory habit, ibr the ''flukes'" are both lu'oad 

 and short and might even increase the powers of the animal 

 in this respect. It thus differs from au interesting example 

 Mr. Punnett procured at Naples in January (PI. III. fig. 2), 

 in which the bifid region was considerably longer than the 

 normal anterior part. INIr. Punnett kindly sent me his notes 

 and figures of this s],ecimen, and these Avill be alluded to 

 shortly. 



The length of the example from Aberdeen is 30*7 centi- 

 metres. In its contracted condition (PI. III. fig. 1) the anterior 

 third is massive, pointed at the snout, and diminishing 

 posteriorly to a flattened body with its thin margin. It 

 tapers gently to the bifurcation, where its transverse diameter 

 is 18 mm. The left limb of the fork, which comes off at 

 right angles to the main axis, is the larger and longer, 

 * Q. J. Mic. Sc. vol. xliv. N. S. p. li'2. 



