TWO NEW LARVAL NEMATODES BELONGING TO THE 



GENUS PORROCAECUM EROM MAMMALS OE THE 



ORDER INSECTIVORA 



By Benjamin Schwartz 



Of the Zoological Division, Bureau of Animal Industnj, United States 

 Department of Agriculture 



Under date of October 22, 1924, Dr. Paul Bartscli of the United 

 States [National Museum, forwarded to this laboratory encysted lar- 

 val nematodes, collected by Miss E. A. Cook from under the skin of 

 a short-tailed shrew {Blarina hrevicauda) in the District of Colum- 

 bia. The cysts are spherical in shape, from 2 mm. to 4 mm. in maxi- 

 mum diameter, each containing a spirally coiled nematode, visible 

 through the rather transparent cyst wall. Two nematodes were freed 

 from their cysts by dissecting the cyst wall and several cysts were 

 cleared without injuring the cyst wall. Examination of the worms 

 showed that though they were sexually immature, they could be 

 readily identified as belonging to the genus Pormcaecum, on the 

 basis of the oblong esophageal ventricuhis, the absence of an eso- 

 phageal appendix, and the presence of an intestinal cecum. 



Owing to the feeble development of the lips and accessory mouth 

 structures in the worms in question it is neither possible nor desirable 

 to assign them to any of the known species of the genus, and follow- 

 ing a common usage among zoologists, these parasites, though sex- 

 ually immature and otherwise incompletely developed, are given 

 specific rank, the name Porrocaecum encaq)sulatum being proposed 

 for them. 



PORROCAECUM ENCAPSULATUM, new species 



Immature worms, occurring in globular cysts from 2 mm. to 4 mm. 

 in maximum diameter, lodged under the skin of the host. The 

 worms are long, slender, superficially resembling filaria, lying 

 spirally coiled within their cysts (fig. 8). The cuticle is striated 

 transversely throughout the entire length of the worms. One speci- 

 men extracted from the cyst measures 36 mm. in length by 0.365 mm. 

 in maximum width. The head v>'hen viewed from the side shows 



No. 2589.— Proceedings U. S. National Museum, Vol. 67, Art. 17 



29111— 125 1 



