112 ILLINOIS BIOLOGICAL MONOGRAPHS [400 



fish, SO far as the writer is aware) estabhsheci the fact "dass seine Larven in 

 den verschiedenen Fischen oder Tieren, welche von Rochen {Raja clavata) 

 gefressen werden, sich befanden." 



From the foregoing description it is to be seen that this form is very closely 

 related to the B. scorpii (Miiller) of Europe, altho in many respects it is so 

 different as to almost warrant the erection of a new species to accommodate it. 

 However, on account of the fact that several forms of the European species 

 have been reported, namely, B. scorpii forma hibalidis and forma motellae by 

 Lonnberg (1889:32 and 1893:13) and those from Rhombus maximus and Cottus 

 quadricornis by Schneider (1902a:14 and 1903:75), it is considered that here in 

 America one finds the same species as has been found in Europe. And from a 

 comparison of the measurements given above with those given by Leidy (1855: 

 444) and Linton (1890:732, 734 and 1897:430), it seems that, little as one can 

 rely on external measurements, they also point to definite differences of habit 

 as this worm is found in different host species on this side of the Atlantic. 



In the table given below under B. clavkeps the important diagnostic data 

 of this form are placed alongside those of the European species for the sake of 

 comparison. 



The material studied consisted of lots Nos. 191, 196, 197, 198, 287, and 288 

 of the writer's collection from the intestine of Hemitripterus americanus 

 (GmeUn), No. 17.57 of the Collection of .the University of Illinois from the 

 same host, and No. 17.56 of the same collection from Myoxocephalus aeneus (?). 



DIBOTHRIUM ANGUSTATUM (Rudolphi), species inquirenda 



Linton (1901a :454, 474) reported this species from Poronotus triacanthus, 

 the butter-fish, and Merliiccius bilinearis, the silver hake. Regarding speci- 

 mens from the former he said: "9. Dibothrium angustatmn Rudolphi. Intes- 

 tine [PL XXIV, figs., 269, a, b, c] 



Thirty-seven young strobiles, August 21, 1899. These agree closely with 

 Diesing's synopsis of this species: 'Head elongate, tetragonal, slender, with 

 oblong lateral bothria; neck very short. First segments elongated, very nar- 

 row, succeeding segments shorter, subquadrate. ' 



The outline of the head varies with the state of contraction, but the pre- 

 vailing form is linear, oblong or somewhat clavate. Segments slender, almost 

 cylindrical, slightly enlarged at their posterior ends. Dimensions of an alco- 

 holic specimen in millimeters: Length of head, 1.16; breadth, anterior 0.33, 

 greatest breadth 0.33, posterior 0.19. Another: Length of head 1.21, breadth 

 anterior 0.22, greatest breadth 0.26, posterior 0.17. Longest head measured 

 1.92mm. in length to the first distinct segment. The strobiles are linear or 

 nearly so and measured about 25mm. in length. " 



The species was originally created by Rudolphi (1819:476) to accommodate 

 two specimens from Scorpaena scrofa. The diagnosis he gave, however, 

 appHes not only to the anterior end of B. scorpii when much elongated, but 

 also to younger specimens of the same. "Ovaria speciei praecedentis [B. 

 punctatus — mihi] cUi haec etiam valde affinis est," from the same description 



