AN ABNORMAL CESTODE PROGLOTTID. 1 



EDWIN LINTON. 



In the summer of 1905, while engaged in work for the Bureau 

 of Fisheries at the Woods Hole Laboratory I found an interest- 

 ing cestode abnormality, a description of which is here given. 



Among a lot of free segments of the cestode Calyptrobothrium 

 occidental? Linton from the torpedo, I noticed one which had 

 two reproductive apertures upon one of the lateral margins. 

 Upon flattening this segment under a cover-glass it was found to 

 be double. The reduplication can be best explained in general 

 by saying that it is such as would be formed if two normal pro- 

 glottids were to grow together by their anterior ends. 



The specimen was fixed over a flame, and after the customary 

 hardening was stained with borax carmine and mounted in bal- 

 sam. Fig. i was sketched from the mounted specimen. The 

 specimen measured 4 millimeters in length and 2 millimeters in 

 breadth. 



As may be seen by an examination of the figure the specimen 

 would give rise to two complete proglottids if it were transversely 

 bisected midway between the two reproductive apertures. At 

 the opposite ends will be seen the lobed ovaries (o, o) arranged 

 symmetrically on either side of the median line, with the shell 

 gland (sg, sg) between the two lateral masses of the ovaries and 

 toward the extremity of the proglottid. 



The reproductive apertures are on the same lateral margin, 

 each being approximately not far from one third the total length 

 of the double segment from one end. 



Each of the two parts, considered by itself is a normal segment, 

 so far as the general arrangement of the various organs is con- 

 cerned, except that there is relatively less space taken up by the 

 testes (f) which are massed together in the median region and 

 possessed in common by the two component parts of the double 

 segment. 



The vitelline glands (vg, vg) are continuous along the margin 



1 Published by permission of the Bureau of Fisheries. 



