78 Prof. M'Intosli's Notes from the 



" Sucli exiicrimcnts, however, refer to segmented animals; 

 whilst one of the most interesting points aljout this spe- 

 cimen is that it is a case of bifidism occurring in an animal 

 which does not exhibit the phenomenon of nietameric seg- 

 mentation. Possibly the experimental study o£ regeneration 

 among the Nemertines might throw some light on an instance 

 such as this.'' 



In the example from Aberdeen the bifid tip is beyond the 

 region of tlie proboscidian sheath. The alimentary canal 

 is thus the sole chamber which becomes bifid, and much 

 of it has fallen out from imperfect preservation, so that only 

 the body-wall and the gut-pouches appear in sections *. 

 It is evident, however, that the inner nerves appear, as 

 ]\Ir. Punnett describes, within the arch of the fork, and pass 

 to each limb, whilst the original nerves continue their course 

 externally. A brief examination of the structure of the inner 

 nerves (that is, those placed on the inner border of each fork) 

 revealed no very evident distinction from the outer trunks, 

 the nervous structure of the sheath apparently having similar 

 elements in both. The tissues, however, may have been 

 altered by the imperfect preservation, and yet, in a specimen 

 so large, even a slight difference in the neurochords would 

 have been noted. 



The '^[edMeYvawedinCerebratulusmarginatus, Renier (1804), 

 which Burger identifies M'ith the Cerebrutulus amjidalm, O. F. 

 JMliller, of the 'British Nemerteans/ presents marked differ- 

 ences in coloration from the British form, and is also much 

 sn^aller, but such may be due to variation. Burger does not 

 allude to O. F. Miiller's form in this connexion. 



4. On Araphiporus hastatus, M'Intosh. 



The; occurrence of a very fine example of ximphiporus 

 hastatus, i\l'I., affords an opportunity for a few additional 

 remarks on its aspect and structure. It was found by the 

 experienced attendant at the Laboratory (A. W. Brown) 

 whilst digging for littoral forms near low-water mark, in sand 

 near the Burn-stools (rocks), and in the same line of beach 

 in which rare Nemerteans and Annelids have so often been 

 obtained. It was in a tube of mucus and sand, sufficiently 



* For these sections I am indebted to Dr. J. R. Tosh and Mr. R. M. 

 Craig, who carried out the somewhat diihcult task of following the 

 structure of the separate tails. 



