SOUTH AMERICAN NEMATOGNATHI. 51 



DOUBTFUL OR INSUFFICIENTLY CHARACTERIZED SPECIES OF 

 PYGIDIUM. 



I. Pi/gidiiLm/uscHmMeyen; II, III and IV. Tricliomyc- 

 terns tigrinum, jjcdlens & marmovatas Philippi; V & YI. 

 Tricliomyderus tenuis and corduveiisis AVeyenbergh. 



3. Pygidium macraei (Girard). 



. Locality: Uspullatuo, 



4. Pygidium maculatum (Cuv. & Val.) 



Locality: Eio Mapocho, Chile, 



5. Pygidium areolatum (Cuv. & Val.) 



Locality: Eio Mapocho, Chile. 



6. Pygdium rivulatum (Cuv. <fe Val.) 



IVkhomyderus incce, gracilis, and harhatula Cuv. «fe Val.; Tr'ichomyc- 

 terus pictiis and pentlancU Castelnau; Trichomycterus d'lspar Giinther . 

 Localities: Cuzco; Moho & Pnno on Lake Titicaca. 



7. Pygidium poeyanum Cope. 



8. Pygidium brasiliensis (Keiuhardt). 



.? Trichomycterus brasiliensis tristis Liitken. 



Localities: Rio Parahyba; Mendez; Lagoa S;inta; Santa Cruz. 



9. Pygidium taenia (Kner). 



10. Pygidium laticeps (Kner). 



11. Pygidium oroyae pp no V. 



Types, No. 3955; eight specimens .115-. 14 m. Pochachara, Oroya 

 Piiver. Closely allied to P. brasiliensis. 



Eather robust; head about as long as wide, none of the 

 barbels reaching gill -opening when laid straight back. 

 Gill membrane narrowly joined to the isthmus, without a 

 free margin. 



Pectoral short, fan-shaped, the first ray not prolonged. 

 Dorsal inserted over the vent, its last ray over or behind 

 the middle of the anal; its origin equidistant from anterior 

 margin of eye or occiput and tip of caudal. 



Caudal broadly rounded, its distance from the anal 4-4} 

 in the length. 



