ABT. 2] . 



PARASITES OF SHARKS AND SKATES LINTON. 



97 



A few specimens of an Orygmatohothrium and one Thysanocepluv- 

 Imn thysanocevhalum were found in the spiral valve. 



In the stomach I found 41 examples of a T etrarhyncTm^ which, 

 upon superficial examination, suggested both T. hisulcatus^ and T. 

 rohustiis. 



Most of them were adhering to the stomach wall. Wlien removed 

 they still showed a tendency to fasten themselves again to the stomach 

 wall and to each other. 



Following are a few measurements of examples of four species of 

 Tetrarhynchus. Wliile there is much variation in the dimensions of 

 these soft bodied worms, especially in preserved material, a record 

 of dimensions is not devoid of value for purposes of comparison. 

 Measurements made from material mounted in balsam. 



Dimensions. 



Length of strobile 



Length of scolex 



Length of bothrium 



Diameter of scolex through bothria 



Diameter of neck behind bothria 



Diameter of neck (collar), posterior 

 end 



Length of collar 



Length of contractile bulb 



Diameter of contractile bulb 



Length of probos-^is 



Diameter of proboscis, base, includ- 

 ing hooks 



Length of hooks, maximum 



Length of posterior proglottis 



Breadth of posterior proglottis 



T.ro- 

 bustus. 



T.ro- 

 hustus. 



15. 00 15. 00 



1.00 0.91 



0. 56 0. 49 



0. 63 0. 51 



0.45 1 0.35 



0.40 

 0.19 

 0.30 

 0.10 

 0.64 



0.39 

 30 

 0.27 

 0.10 

 0.50 



0. 03 0. 045 



0. 006 0. 015 



0. 70 



1.12 



T. bisul- 

 T.hisul-i cat-as, 

 cuius. I com- 



ipressed. 



76.00 llOO.OO 

 1.28 1 1.68 



0.70 

 0.81 

 0.52 



0.39 

 0.18 

 0.31 

 0.10 

 0.70 



0.84 

 1.29 

 1.05 



0.80 

 0.42 

 0.46 

 0.22 



0.06 1 0.06 



0.02 ! 0.018 



0.46 I 0.98 



1.42 2.10 



T. pal- 

 laitus. 



30.00 

 1.82 

 0.76 

 0.93 

 0.84 



1.28 

 0.70 

 0.39 

 0.14 

 0.50 



0.06 

 0.021 

 0.60 

 2.36 



T. pal- i 

 laiius. 



20.00 

 1.93 

 0.77 

 0.70 

 0.53 



1.19 

 0.70 

 0. 35 

 0.14 

 0.53 



0.06 

 0.019 

 0.49 

 1.33 



T. 



teuue. 



10.00 

 0.67 

 0.38 

 0.26 

 0.15 



0.15 

 0.07 

 0.12 

 0.03 

 0.32 



0.02 



0.50 

 0.28 



T. 



tenue. 



22.00 

 0.49 

 0.32 

 0.22 

 0.15 



0.14 

 0.08 

 0.09 

 0.04 



0.77 

 0.63 



The proboscis of T. rohvstus tapers from the base to the tip. For 

 3xample in a proboscis measuring 0.37 mm. in length, the diameter 

 at base, exclusive of hooks, was 0.027, at the tip 0.015; maximum 

 length of hooks 0.009. 



The proboscis of T. hisulcatus remains practically the same diam- 

 eter from base to tip. Thus, in a proboscis 0.70 mm. in length, the 

 diameter at base, exclusive of hooks, was 0.048, at tip 0.045 ; length 

 of hooks near base of proboscis, 0.015, near tip 0.024. 



In T. palliatus the proboscides are of the same type as those of T. 

 hisulcatus. In a proboscis 0.53 in length, the diameter at base, ex- 

 clusive of hooks, was 0.030, at tip, 0.027; length of hooks near base 

 0.015, at tip 0.021. No proboscis in this species was seen fully ex- 

 tended. 



