2 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 60. 



ing themselves. In the first place the worjns of each lot differ 

 slightly but constantly from the figures and description of D. sep- 

 taria. In the second place, when the scoleces of the two lots were 

 compared one with the other they were found to be unlike in many 

 details. 



The scoleces of the worms from the bone shark have long strobiles 

 with ripe proglottides attached to them, while those from the man- 

 eater shark are smaller and have short strobiles with only immature 

 proglottides. Consequently one must rely very largely on the sco- 

 leces in a comparative study of the two forms. 



It should be noted that we are here dealing with cestodes from 

 selachians, which are generically different from each other, and 

 generically different from the host of D. septaria. Further, the 

 species D. plicitum, whose scolex appears to differ rather more from 

 D. septaria than does D. planum, is from a host which belongs to 

 the same family as Lamia, that is the Lamnidae, or mackerel sharks. 

 On the other hand, D. planum, whose scolex resembles D. septaria 

 rather more closely than does D. plicitum, is from a host which be- 

 longs to the family Cetorhinidae, or basking sharks. 



The following adaptation from Beneden's description of D. septaria 

 is in agreement with the forms from CarcTiarodon and Cetorliinus 

 and maybe taken, therefore, as characters of the genus Dinohothrium: 

 Bothria four, in pairs placed back to back, without hooks, large, oVal, 

 attached the entire breadth of the base, the external face concave, 

 and surmounted above by a projection. Above each bothrium there 

 is a little sucker, and outside the sucker the part which supports the 

 lobe is terminated by a short appendage. 



Regarding the cestodes, which furnished the basis of this report as 

 new species, the genus Dinohothrium is represented by the following 

 species: 



Dinobothrium septaria Beneden. Hosts: Lamna cornubica. 

 Dinobothrium plicitum, new species. Hosts: Carcharodon carcharias. 

 Dinobothrium planum, new species. Host: Cetorhinus maximus. 



DINOBOTHRIUM PLICITUM, new species. 



Figures 1, 4, 5, 6. 



Dinobothrium septaria Beneden, Linton, Bull. Bur. Fish. (1911), vol. 31, pt. 

 2, p. 586. 



Type.— Chi. No. 7601, U.S.N.M. 



The material upon which this description is based was collected 

 from the spiral valve of a small man-eater shark, 4 feet in length, at 

 Woods Hole, Massachusetts, September 1, 1903. The contents of 

 the stomach consisted of fish and squid. 



The following are extracts from notes made at the time of col- 

 lecting:: 



