NATURAL SCIENCES OF PHILADELPHIA. 17 



formations described. After explaining the manner in which the 

 thin sections were prepared, the following specimens were ex- 

 hibited : A piece of Diorite from the northeastern corner of 

 Saxony, a foliated chlorite slate, ferruginous gneiss. Nes'silicon 

 steel ore, Diorite, qnartzite rock with magnetic iron ore from the 

 northeastern part of York County, hornblende slate, limestone 

 containing particles of a substance probably apatite, a syenite 

 from Germany, with hornblende, quartz, and orthoclase, and a 

 syenite from near Gettysburg. The gizzard of a cockroach was 

 also exhibited and shown to produce beautiful colors in polarized 

 light. 



February 9. 

 The President, Dr. Ruschenberger, in the chair. 

 Nineteen members present. 



Notes on some Parasitic Worms Prof. Leidy exhibited some 



nematoid worms, on which he made the following remarks: 



One of the species is common in feline animals, and is the Asca- 

 ris mystax. The specimens, consisting of fifteen females and five 

 males, had been sent to Dr. Chapman, by Mr. Thompson, Superin- 

 tendent of the Zoological Garden, who reports that they had been 

 passed by the American wild-cat. The females measure from 2^- 

 to 4 inches in length, by to of a line in thickness. The males 

 measure from 2^ to 2^ inches in length, by ^ to ^ a line in thick- 

 ness. The specimens are larger, and the alas of the head propor- 

 tionally better developed, and therefore more conspicuous than in 

 those noticed at the previous meeting as having been passed by 

 the Bengal tiger. The worms of the tiger are such as have been 

 described under the name of Ascaris leptotera, which appears to 

 be only a variety of A. mystax. 



The other worm is a Filaria, apparently an undescribed species. 

 Half a dozen individuals of the two sexes were obtained from the 

 peritoneal cavity of an Australian Whallabee, which recently died 

 in the garden of the Zoological Society. The characters of the 

 parasite are as follow: 



Filaria spelasa Body filiform, translucent wdiitish, tapering at 



the extremities. Cephalic end straight, obtusely rounded, fur- 

 nished with four equidistant papillre around the mouth. Caudal 

 end narrowest, rather abruptly attenuated, and spirally rolled once 

 or twice, and terminating obtusely. A distinct anal aperture ob- 

 servable in the female. A row of eight papillae on each side ven- 

 trally of the caudal end of the male; three in advance and the 

 others back of the genital aperture. Penis a long, tubular style, 

 thick at the upper part, narrow and curved below. Accessoiy piece 

 a short, thick, curved tube, widening at the upper end in a spade- 

 like, furcate portion. 



