292 MISS EDITH E. BAMFORD ON THE 



fibres being external and the circular fibres internal {op. cit, pi. v. 

 fig. 4). As a conseqvience, the lower end of the body exhibits 

 great variability of form, sometimes presenting the same diameter 

 as the rest of the ampulla, at other times dilating to a sphere, 

 and again attenuating to an elongated process. Its special 

 function in the adult is to bury the animal in the mud of the 

 sea-floor. 



The function of the foot-disc of the newly-transformed Phoronis 

 seems to be the attachment of the body to the substratum. It is 

 desirable to distinguish between a postlarval and an adolescent 

 phase. So far as I am able to judge from the work of M. de 

 Selys-Longchamps, the peristaltic contractility of the hinder 

 division of the ampulla in the mature or submature Phoroids is 

 not identical with the metabolic contractility of the foot-disc in 

 the postlarval phase, when it is associated with, though not 

 in any way caused by, the reti-actility of the csecal capillaries at 

 this stage. In other words, the formation of the adhesive 

 foot-disc precedes that of the burrowing ampvdla. 



I believe this is the first record of the occui-rence of Phoronis 

 on the eastern coast of Canada. No specific description can be 

 based upon a single specimen which has just undergone the meta- 

 morphosis ; but if my identification of the larva is correct, then 

 the species may be named provisionally Phoronis hroionei. 



In conclusion I desire to acknowledge the kindness and 

 attention which I received from Dr. A. G. Huntsman, the 

 energetic and obliging Superintendent of the Station. 



23. Variations in the Skeleton of the Pectoral Fins of 

 Foil/pi erus. By Edith E. Babiford, Newnham College, 

 Cambridge *. 



[Received January 22, 1913 : Read March 18, 1913.] 



(Text-figures 56-60.) 



Index. 



Page 

 Variation and -iEtiology 293 



It was suggested to me bj' Dr. Gadow that the examination 

 of the individual variations of the ample material of young and 

 adult Polypterus collected by Budgett in his Gambia and Niger 

 Expeditions, now the property of the Cambridge University, 

 might account for the discrepancies which are found in de- 

 sciiptions of the pectoral fins of Polypterus. After examining 

 the material, it becomes evident that these discrepancies are 

 mostly the result of the many individual variations and of the 

 former scarcity of ma,tei'ial. A desciiption of the variations 

 found in the ample material at my disposal is of future value ; 



* Communicated by Dr. H. Gadow F.R.S., F.Z.S. 



