208 



The Philippine Journal of Science 



1917 



mouth and anterior sucker, which is the most important charac- 

 teristic of the genus Echinostoma. Garrison failed to note these 

 spines in any of the specimens which he studied, and Odhner 

 says of the four specimens sent him by Garrison that "the 

 arrangement of the spines can only be followed in one specimen," 

 From our 16 specimens we obtained only 3 in which any traces 

 of these spines could be seen, and in only one specimen were 

 they in a condition such that their arrangement could be studied. 

 It seems that these spines, although much larger, are even more 

 unstable than those of the cuticle (Plate I, fig. 1). 



In the specimen described by Odhner 49 spines were present, 

 which were arranged in the form of a wreath around the oral 



0.4 mm 



Fig. 1. Outline drawing of anterior end of Echinostoma ilocanum (Garrison), showing the 

 arrangement of the oral wreath of spines. 



sucker, broken on the ventral side. There were two corner 

 groups next to the ventral opening of 5 and 6 spines, respectively, 

 then 2 single spines on each side, followed by 10 spines arranged 

 in pairs, and finally 14 single spines forming the dorsal part 

 of the wreath. The arrangement of the wreath in our specimen 

 may be seen in fig, 1. As will be seen, there are only 39 

 spines present, but their arrangement is very much the same 

 as described by Odhner. There are the two corner groups, the 

 single spines, then the paired spines, and the row of dorsal 

 spines. From a study of their arrangement it can be seen that 

 several spines on our specimen have been lost. 



The size of the spines in different parts of the wreath varies 

 considerably. The largest ones in the comer groups are 50 mi- 



