1S49.] 233 



In the state in which Gregarina is found, it would probably hold a rank between 

 the Trematoila and Trichina the lowest of the Nematoidea. 



Tiyctntherus,* a new gemis of Polygastrica, allied to Plesconia. — Body ovate, 

 dilated posteriorly, compressed anteriorly, granulated, longitudinally lined, 

 with an apparent operculum covering its anterior half, and having a semi-circle 

 of cilia just within its margin inferiorly and posteriorly. Centre of the 

 operculated portion furnished with a large trapezoidal finely granular areola. 

 Posterior part of the body with a short fissure passing inwards and downwards. 



Nyctothenis velox. — Body white, ovate, conoidal, anterior margin rounded, 

 obtuse; posteriorly acute< Posterior margin of the apparent operculum passing 

 in a curved line upwards upon the middle of the body to within a short distance 

 of the back, and furnished inferiorly with a point projecting backwards. With a 

 line passing down from the back about the middle of the operculum to the trape- 

 zoidal areola, giving the part of the body anterior to this the appearance of a 

 head. Trapezoidal areola, with curved sides, finely granular. Posterior fissure 

 communicating with the exterior, just above the acute termination of the body, 

 and passing inwards and downwards, resembles an anal aperture. Areolae of the 

 interior sarcous mass generally minute, one large and round pretty constantly to 

 be observed at the inner termination of the posterior fissure. 



Length from l-254th to 1-lSOth in.; breadth from l-320th to l-254th in. 



Habitat. — Commencement of the large intestine of Julus marginatus, often 

 found in considerable numbers. 



Remar/cf. — This genus is closely allied to Plesconia, but possess no appendages 

 excepting the semi-circle of cilia, just within the edge of the apparent operculum. 



The animal swims in water with great ease and grace. After being in this 

 fluid some time, the external investment bursts, and allows the protrusion of 

 globular masses of sarcous matter, as in Leucophrys, but not to such a great 

 extent. 



Note. — Since the above went to press, Dr. Leidy announced to the Academy 

 that he had discovered two new species of the entophyte P'nterobrus ; one of them, 

 E. spiralis, l-69thinch long, growing in the small intestine of Julus pusillus ; the 

 other, E. attenuatus, l-24th inch long, growing more or less profusely with a 

 second species of Cladophytum,C. clavatum, in the ventriculus of a coleopterous 

 insect, Passalus cornutus. Thus has been established the law "that plants may 

 grow in the interior of the healthy animal as a normal condition," and a new field 

 has been presented for the investigation of the Cryptogamo-naturalist. [See forth- 

 coming number of the Proceedings.] 



October l^th. 



Mr. Pearsall in the Chair. 



Mr. Cassin read a paper describing some new species of Birds, of 

 the family of Caprimulgidse, specimens of which are in the collection 



* Nvxfoe/jpoj. 

 32 



