NO. 2131. NEMATODE PARASITES OF RODENTS— HALL. 169 



anterior, near the posterior end of the esophagus. Oviparous, the 

 egg containing a well-developed embryo when oviposited. Parasitic 

 in the small intestine as a rule. 



Type-species.— Rictularia cristata Froelich, 1802. 



ANALYTICAL KEY TO SPECIES OF IlICTITLAEIA. 



1. Female less than 15 mm. long; about 34 cuticular combs in each row from 



the head to the transition point near \\\\\ii— Rictularia coloradensis, p. 173. 



Female more than 15 mm. long; less than 30 or more than 40 combs in the 



row from the head to tlie transition point near vulva 2. 



2. Female with 50 combs from head to transition i>omt— Rictularia falla.v, p. 171. 

 Female with not over 20 coml)S from head to transition point 3. 



3. Female with 2 cervical alae with small spines on edges. 



Rictularia elvirae, p. 170. 

 Female without cervical aUie Rictuhtria cristata, p. 1G9. 



No male of the above species is known except that of B. colora- 

 densis. See Addendum for Rictuluria proni Seurat, 1915. 



RICTULARIA CRISTATA Froelich, 1802. 



SynonyTTis. — Ophiostoma cristatuni (Froelich, 1802) Eudolphi, 

 1819; Ophiostomum cristatuni (Froelich, 1802) Diesing, 1851. 



Specific diagnosis. — Rictularia (p. 1C8) : 



Male unknown. 



Female 22 to 27 mm. long (Dujardin gives this as 

 16 to 66 mm. long and 400 fx to 1.32 mm. thick) . Red 

 when freshly collected. Head 280 p. in diameter. 

 Esophagus simple, 4.3 mm. long and 300 /x thick. The 

 head (fig. 210) terminates in a thick lip, rounded in 

 the form of a helmet, and bears several small papillae. ^'°- 2ic.-Rictu- 



' _ _ -•■ ^ . LAKIA CRISTATA. 



The mouth aperture is transverse, reniform, or semi- anterior ex- 

 circular, and is 180 a in diameter. It is bordered an- Tfrj"" ""V^' 

 teriorly by a row of a dozen small teeth and also poste- larged. af- 

 riorly by a row of 12 to 15 small teeth borne on the in- ^''2 froeuch, 

 ferior lip. The vulva is a large transverse slit located 

 just back of the posterior end of the esophagus and a little lateral of 

 the ventral line (fig. 217). The vagina passes posteriorly from this 

 and is 1.3 mm. long and 260 ^ thick. This bifurcates to form two con- 

 \ergent uteri, 150 ju, long or longer, terminating in filiform ovaries. 

 Eggs elliptical, Vv^ith an inner thick shell 41 ju, long and an outer thin 

 shell 50 [i long. Eggs with well-developed embryo when oviposited. 

 The cuticle bears from the head to the vulva two rows of 18 to 20 cuti- 

 cular combs, finely striated, set close together, and not very prominent. 

 One or more combs visible posterior of the vulva. (A row of widely 

 spaced cuticular spines is probably present from the vulva to the 

 posterior end of the body.) The thick conical tail is short and blunt 



