136 BULLETIN 140, UNITED STATES NATIONAL MUSEUM 



l J ype-species. — Porrocaecum, crassum (Deslongchamps, 1824) Rail- 

 liet and Henry, 1912. 



KEY TO SPECIES OF PORROCAECUM 



1. Larva only known, in eel, Anguilla vulgaris Porrocaecum anguillae, p. 146. 



Adults known, In birds 2. 



2. Lateral membranes present 3. 



Lateral membranes absent or undescribed 5. 



3. Cecum long (about 3 mm.) Porrocaecum serpentulus, p. 142. 



Cecum short (apparently not longer than ventriculus) 4. 



4. Lips with 1 papilla, situated medianly ; female tail 1/50 to 1/63 of total length ; 



eggs 91/4 long by 85/i wide Porrocaecum semiteres, p. 141. 



Lips with 2 large oval papillae ; female tail 1/46 of total length ; eggs 110/t 

 long by S5/i wide Porrocaecum ensicaudatum, p- 139. 



5. Species unrecognizable ; possibly identical with F. ensicaudatum. 



Porrocaecum heteroura, p. 144. 

 Species recognizable 6. 



6. Conspicuous gubernaculum present ; male with 3 pairs of postanal papillae 



(2 of them very small, on the caudal appendage, the other pair large but 

 simple, a little posterior to cloacal aperture). 



Porrocaecum reticulatum, p. 141. 

 No gubernaculum described ; postanal papillae, where described, more nu- 

 merous than 3 pairs except in P. spirale, where the pair near the cloacal 

 aperture is made up of double papillae 7. 



7. Vulva posterior to middle of body 8. 



Vulva anterior to middle of body 9. 



8. Lips described only as convex in shape ; male not over 30 mm., female not 



over 53 mm. long ; from Anas, species and Numida meleagris. 



Porrocaecum crassum, p. 136. 

 Lips six-sided, with digitif orm projections of pulp ; male up to 48 nam. 

 long ; female up to 64 mm. long ; from other hosts than above. 



Porrocaecum spirale, p. 143. 



9. Female 154 mm. long. Male said to have caudal alae anterior to the 



cloacal aperture, supported by 5 pairs of papillae ; from Colymbus 



auritus Porrocaecum praelongum, p. 140. 



Female not over 112 mm. long ; male without caudal alae ; from other hosts 



than above 10. 



10. Dorsal lip with pulp divided into 2 bipartite lobes and between them a 

 rounded lobe ; pulp not notched toward base but follows outline of lip. 



Porrocaecum depressum, p. 137. 

 Pulp divided into 2 rounded lobes from the inner surface of which project 

 2 broad flat plates ; toward base of lip pulp sharply notched with a promi- 

 nent cuticular band opposite the notch Porrocaecum angusticolle, p. 137. 



This key does not include Ascaris kirghisensis (p. 145), which the 

 writer has placed tentatively in Porrocaecum but which may prove 

 to be a species of Contracaecum. 



PORROCAECUM CRASSUM (Deslongchamps, 1824) Railliet and Henry, 1912 



Synonym. — Ascaris crassa Deslongchamps, 1824. 

 Hosts. — Anas boschas, A.b. domestica, A moschuta, Numida mele- 

 agris. 

 Location. — Small intestine. 



