830 WINTERTON C. CURTIS 
therefore that the three weeks without food had produced no 
effect. In eight of the fish there were a considerable number of 
young specimens of C. laciniatum in all stages of proglottid 
formation, but as similar stages are commonly found in all sharks 
(Curtis, 03 and ’06), their occurrence here was no evidence that 
they had come from the introduced Scolex polymorphus, and the 
diversity of their stages made any such interpretation out of the 
question. In these eight specimens there were found in addition 
to the young and adult C. laciniatum, an unusual number of 
individuals of the species Crossobothrium angustum, which Lin- 
ton (99) p. 426), records as a frequent parasite of the dusky 
shark, Carcharinus obscurus, and the blue shark, C. milberti. 
Although present in greater numbers than I have found in any 
other lot of sand sharks, these C. angustum were of all stages from 
young to adult and there seemed, therefore, no evidence which 
would connect them with the larvae which had been introduced 
by my infection. In the whole number of sharks I found upwards 
of fifty young of another cestode, ali in about the same stage, and 
with well developed scolices and the segmentation into proglot- 
tids just beginning. Because of their conspicuous and charac- 
teristic bothria, these were at once recognizable as the young of 
the species Phoreibothrium triloculatum, a form which Linton 
has described from the dusky shark and which is represented in 
figs. 5, 6, 9, 10 and 11 of this paper. Unfortunately, my 
records give only the fact that each of these sharks contained 
some Phoreiobothria and fail to give their distribution in the 
individual sharks. 
The occurrence of this species in the sharks of this experiment 
would indicate, when taken alone, hardly more than that P. 
triloculatum is sometimes found in the sand shark, even though 
the only sand sharks in which I have found it are the ones pre- 
viously infected with the Scolex polymorphus. The fact that the 
individuals were all of about the same early stage is more import- 
ant, though not much stress can be laid upon it because of the 
failure of my records to state the distribution of these worms in 
the individual fish. I regard the results of this attempt at infec- 
tion, which was the only one I was ablesto carry through in the 
