1888.] NATURAL SCIENCES OF PHILADELPHIA. 169 



sciences of geology and paleontology, or in such particular branches 

 thereof as may be designated. The award and all matters connected 

 therewith are to be determined by a committee to be selected in an 

 appropriate manner by the Academy. 



May 8. 



The President, Dr. Leidy, in the chair. 



Eighteen members present. 



The following papers were presented for publication : — 

 "On the formation of rock-salt beds and mother-liquor salts."' 

 By Dr. Carl Ochsenius. 



" Description of a new species of Ocinebra." By John Ford. 



Parasites of the Pickerel. — Dr, Leidy remarked that among the 

 numerous parasites which are mentioned as infesting the Pike, Esox 

 lucius, of Europe, no Taenia is indicated. In the Pickerel, Esox retic- 

 ttlatus brought to our market, a species of the latter appears to be 

 common. In two fishes he found half a dozen, in the intestine and 

 stomach; and in another a single individual two feet in length. It 

 resembles closely the Tcenia amhloplitis, noticed in the Rock Bass, 

 Amhloplitis rupestris (Proc, 1887, 23) and may be the same. Dis- 

 tinguishing it with the name of Taenia leptosoma, its characters 

 are as follow : Body long, and thin, and at the fore-part thread- 

 like. Head unarmed, without rostellum, with four equidistant 

 hemispherical bothria ; neck very short or none ; anterior segments 

 transversely linear, many times wider than long ; posterior segments 

 gradually becoming proportionately longer and quadrate and barrel 

 shaped ; genital apertures marginal, alternating irregularly. Ova 

 spherical. 



Length from six to nine and twenty six inches, shortening to one- 

 half or less ; breadth to 2 and 2-5 mm. Head 0*25 to 0-5 mm. broad ; 

 bothria 0"125 to 0"175 mm. Anterior segments an inch from the 

 head 0"175 mm. long by 1 mm. broad; posterior segments 0"5 to 

 0-75 mm. long by 2 to 2-5 mm. broad. Ova 0*028 to 0-032 mm. in 

 diameter. 



A single slender Scolex associated with the longest Taenia was 4 

 mm. long by 0*25 wide, but elongated to 8 mm. by 0"1 wide. The 

 head was of tiie same form as that of the Tcenia. After being in 

 alcohol, the head of the Scolex was 0"225 mm. wide with the bothria 

 0"1 mm. in diameter. The posterior part of the body exhibited traces 

 of segmentation, with the segments 0"075 mm. long by 0"25 wide. 



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