18/6. J UK. T. S. tOBBOLD OxN ENTOZOA. 295 



Zoological Gardens. Some of these have been described in the So- 

 ciety's ' Proceedings ;' and others have been publicly noticed elsewhere 

 in a less formal manner. 



Amongst the series in question was a bottle that contained three 

 different species of nematoid parasites, all derived from one and the 

 same host. The infested animal was a Lemur (Pithecia leucocephala) 

 which appears to have died at the Gardens on the 28th of June, 1866. 

 The worms were of three well-marked sizes. The largest species, 

 represented by a single parasite and measuring 8| inches long, could 

 not be distinguished from the ordinary Ascaris lumbricoides of the 

 human subject. It had been removed by Dr. Murie from the 

 rectum. 



The worms of intermediate size, numbering in all eleven specimens, 

 were taken from the stomach and oesophagus; six of these were males 

 averaging from an inch to an inch and a quarter in length. The five 

 females varied from \\" to 2" in length. A pocket-lens examination 

 at first suggested that they were examples of Spiroptera dilatata (a 

 species that is common in the South-American Monkeys) ; but [ have- 

 since determined otherwise. The smallest set of parasitic worms from 

 the Lemur, of which there were no less than forty-four specimens in 

 the bottle, proved to be new to science. These had been removed 

 from the small intestine. In the condition in which I received theru 

 they were each thrice or four times coiled upon themselves, remind- 

 ing one of the appearance so often seen in the encapsuled nematodes 

 of fishes. After my original brief examinations, I put all the worms 

 aside for future study ; and it was not until the Kith of April, 1873, 

 that I found the necessary leisure to work out the general structure 

 of these elegant little parasites. Their minute size rendered them 

 eminently favourable for microscopic examination ; and in this way 

 I obtained evidence of the existence of several peculiarities that I had 

 not hitherto encountered amongst the nematodes. The following 

 characters will form a ready means of identification : — Head well 

 marked and famished with a transversely striated bilateral membrane 

 which projects beyond and contributes to the formation of the mouth; 

 oral aperture simple and continuous with a long and moderately nar- 

 row oesophagus ; body decidedly attenuated in front and almost uni- 

 formly thickened behind, its surface being marked by 12 or 14 con- 

 spicuous lines, forming in profile slightly raised parallel ridges ex- 

 tending from one end to the other ; tail of the female suddenly 

 narrowed to a conical point, the arms being placed within a very 

 short distance of its extremity; tail of the male furnished with a large 

 circular and apparently undivided hood, supported by ten rays ; 

 spicule solitary and rather long. Males only i-, and females only ^ 

 of an inch in length. 



In addition to the above diagnosis I may add that I have named 

 the species hemicolor, from the circumstance that the anterior half of 

 the body in nearly all the specimens was a shade darker in colour 

 than the posterior half. I have illustrated the structure of the worm 

 by five figures. One of these affords a general view of the male para- 

 site naturally coiled upon itself (Plate XXI. fig. 5). The longitu- 



