862 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [144] 



The head is tetragonal transverse, cruciform. Bothria four, subcircu- 

 lar, convex, cup-shaped, each the termination of a short cylindrical 

 pedicel. They are arranged in a cruciform manner, but also somewhat 

 in pairs and capable of being directed either forward or backward in 

 pairs. Proboscides very long and slender, each one running through 

 a pedicel and emerging at the apex, apparently beside the bothrium 

 proper. Keck very long and slender, cylindrical, eularging slightly at 

 the contractile bulbs and rounded at the base, tapering to a point, where 

 it is connected with the body (blastocyst) ; proboscis-sheaths spiral, con- 

 tractile bulbs linear oblong ; booklets long and slender, falcate ; blasto- 

 cyst linear oblong, a little longer than the head and neck. 



Dimensions of alcoholic specimen, somewhat flattened: Length of 

 head and neck, 4.60 mm ; length of blastocyst, 5.25 mm ; diameter, 0.76 mm ; 

 breadth of head, about 0.50 mm ; diameter of bothrium, 0.12 mm ; diameter 

 of pedicel, 0.14 mm ; diameter of neck, 0.14to0.30 mm at contractile bulbs; 

 length of proboscides about 3 mm ; length of contractile bulbs, 0.84 mm ; 

 breadth, 0.08 mm . 



The proboscides were retracted but the hooks could be seen through 

 the transparent neck. At the base of the proboscides they were about 

 0.032 mm in length ; near the middle of the proboscides they were 0.0G mm 

 long, with basal supports as much as 0.03 mra wide. The hooks appear to 

 be of pretty uniform shape ; being long, slender, recurved, falcate, with 

 rather broad basal supports. 



I have met with encysted forms similar to this in various species of 

 the Teleostei such as Pomatomus saltatrix, Cybium regale, etc. One 

 from the Spanish mackerel (Cybium regale) was described by me in the 

 American Naturalist for February, 1887, under the name of a larval 

 Tetrarhynchobothrium. 



Family V.— TM1SIMDM. 



Tetracotyleidce Diesing. 

 Parat^enia, gen. nov. 



Body taeniseform, articulate. Head subglobose, with four small op- 

 posite, sessile bothria. Terminal os and sixteen protractile tentacular 

 proboscides. Genital apertures marginal. 



This form appears to be related to the genus Taenia. The tentacular 

 proboscides are probably homologues of the proboscis of avian Tamiwdw. 



43 Paratwnia medusia,* sp. nov. 



LPlate xv, Figs. 5-9.] 



Head somewhat globose but variable according to state of contrac- 

 tion, wider than strobile. Bothria four, small, sometimes papilli- 



* The reference of this species to the Tamkcdce is provisional. Certain structural 

 peculiarities suggest the propriety of referring it to the Tetraboihriidce near Eclienei- 

 bothrium. 



