NO.liQX PROCEEDINGS OF THE NATIONAL MVSEUM. 813 



slender posterior part, all beiug inclosed ill a thin transparent covering. 

 Xo sign of segmentation was observed. 



The most characteristic feature is the prolongation of the anterior 

 ends of the bothrial lobes to form the unarmed basal portion of the 

 I)roboscides. 



A specimeu, slightly compressed, yielded the followiug measure- 

 ments: Length of bothria, IM! mm.; breadth of head, l.G; length of 

 anterior prolongation of bothria, l.S; diameter of same, 0.34; length 

 of proboscides, estimated from retracted organ, G.7."); length of con- 

 tractile bulbs, 2.4; diameter of same, 0.34; length of longest hooks, 0.12. 



Hooks were seen only on the retracted proboscides. They are of 

 very diverse shapes, a few of which are shown in figure 1-'. The 

 arrangement could not be made out exactly. There is a cluster of 

 small bristle-like hooks near the apex (a), preceded at extreme tip by 

 a few large horn-shaped hooks [h). The most abundant type is long, 

 slender, and slightly curved {d). The type {e) constitutes three or four 

 longitudinal rows throughout the length of the i>roboscis. 



17. TETRARHYNCHUS BICOLOR. Bands. 



(Plate Vlir, tigs. 1-6.) 



Bothriocephalus bicolor, Baj;tels, Diesiug, Syst. Helm., I, p. 608. 

 Tetrarhynchohothrium hicolor, Diesixg, Kevis. d. ceph. :ib. I'lir., pp. 316, .317. 



I refer to this species live different lots of larvae of tetrarhyuchus 

 from four species of fish. 



1. From the dolphin {Goryphivrut kippiiriis) (No. 5483, U.S.IST.M.). 

 The specimens in this lot were collected August 13, 1<SS5. The fish had 

 been taken on the Gulf Stream a day or two before: iSTumerous on 

 peritoneum and mesentery. 



2. (No. 4820, U.S.N.M.) From the swordfish {Xijyhias (jladius), off 

 Marthas Vineyard, Massachusetts, July 25, 1887 : three specimens from 

 l)eritoneuin. 



3. (No. 4817, U.S.N.M.) From the dusky shark {GarcTiarhinm 

 ohscurus), Woods Holl, Massachusetts, August 12, 1887; one specimen 

 adhering to mucous membrane in pylorus. 



4. (No. 4825, U.S.N.M.) From the tiger shark {Galeocerdo tigrinun). 

 Woods Holl, Massachusetts, August 14, 1889; five specimens from 

 stomach. 



5. (No. 4829, U.S.N.M.) From the swordfish, i^eritoneum and mes- 

 entery; four specimens. Label reads: "September 21, Trawl line, 

 U. S. Fish Commission." 



These specimens present considerable difference in size and general 

 appearance of the scoleces, but apparently are absolutely ideutical in 

 the arrangement of hooks on the proboscides. The character of the 

 proboscides being so peculiar, particularly the nature of the hooks on 

 the base of the proboscis, that where, as in these cases, only the 



