404 



PATAGONIAN EXPEDITIONS : ZOOLOGY. 



rhosus Gronow; Hypostomus robinii 

 Gill; Plecostomus brasiliensis Bleek- 

 er; Plecostomus seminudus Eigen- 

 mann & Eigenmann ; Plecostomus 

 boulengeri Eigenmann & Kennedy. 

 Habitat: La Plata north to Trinidad; 

 not in southeastern Brazil. 

 2. Plecostomus commersonii (Cuvier & Va- 

 lenciennes), Regan, 206. 



relationships, and for the purpose of discussing the geo- 

 graphical distribution, it will be better to recognize a 

 larger number of genera. My estimate of the character 

 of these can best be expressed by the following key, in 

 which I have followed to a very large extent the 

 phraseology of Regan, but in which are recognized 

 a larger number of genera than are admitted by him. 

 The list of species is accepted with but slight modifica- 

 tions from Regan. 



SUBFAMILIES OF LORICARIIDvE. 



a. Hasmal spines all simple; lower and fourth upper 

 pharyngeals not toothed ; anterior rudimentary ray 

 of ventral normally shaped, but internal and 

 directed forwards, upper part of the body pro- 

 tected by bony scutes. 



b. Lower transverse portion of clavicles and cora- 



coids not exposed ; margin of snout naked or 

 covered with small granular plates. 



Plecostomin/E. 



bb. Lower transverse portion of clavicles and cora- 



coids exposed; margin of snout composed of 



more or less firm plates. Hypoptopomatin/E. 



aa. Haemal spines of the vertebras above the anal fin 



bifid ; lower and fourth upper pharyngeals 



toothed. 



c. No anterior rudimentary ray of ventral ; caudal 



peduncle elongate and strongly depressed ; 

 upper part of body with bony scutes. 



Loricariin^:. 

 cc. Anterior rudimentary ray of ventral internal, 

 plate-like ; caudal peduncle cylindrical or 

 compressed. 

 d. Upper part of body with bony scutes ; abdo- 

 men with a large, regular, nearly square 

 patch of small granular plates, naked at the 

 sides and anteriorly and posteriorly. 



Neoplecostomin.b. 

 Plecostomzn^e. 



a. First scute of lower lateral series posterior to the 



temporal plate, with which the second is not in 



contact. 



b. Premaxillaries nearly equal in length to the den- 



taries, and with about the sanie number of 



teeth. 



Plecostomus spiuigcr Hensel; Pleco- 

 stomus limosus Eigenmann & Eigen- 

 mann ; ? Plecostomus aspilogaster, 

 Cope. 



Habitat : La Plata Basin, including Rio 

 Grande do Sul; eastern Brazil. 

 3. Plecostomus punctatus (Cuvier & Valen- 

 ciennes) , Regan, 207. 



Hypostomus subcarinatus Gastelnau ; 



c. Operculum and interoperculum little, and not 

 independently movable. 

 d. Snout granular to its margin. 

 e. Adipose fin present. 



/. Operculum and interoperculum not 

 margined with bristles. 

 g. Body covered with plates. 



I. Plecostomus Gronow. 

 gg. Body naked. 



2. Lithogenes Eigenmann. 



)]. Operculum and interoperculum with 



well-developed marginal bristles. 



3. Pogonopoma Regan. (Type, 



Plecostomus wertheimeri Steind.) 



ee. Adipose fin absent. 



h. Operculum and interoperculum with 

 well-developed marginal bristles. 

 4. Canthopomus Eigenmann nov. 

 hh. Operculum and interoperculum not 

 margined with bristles. 



5. Rhinelepis Spix. 

 hhh. Adipose replaced by a low median 

 crest. No externally visible oc- 

 cipital crest. 



6. Corymbophanes Eigenmann. 

 dd. Snout with a naked margin. 

 7. Hemipsilichthys Eigenmann & Eigenmann. 

 cc. Interoperculum more or less freely movable, 

 usually spinate or bristly. 

 i. Snout granular to its margin. 

 /. Teeth numerous, bifid. 



k. Interoperculum usually armed with 

 slender spines with hooked apices 

 which can be everted and com- 

 pletely retracted beneath the oper- 

 culum. 

 /. Sides of head without bristles. 

 m. Last dorsal ray connected with 

 the scute by an inconspicu- 

 ous membrane at its base. 

 n. Dorsal with I, 7 or I, 8 

 rays. 

 8. Hemiancistrus Bleeker. 

 HH. Dorsal with I, 10 or 

 I, 13 rays. 

 0,. Pterygoplichthys Gill. 

 mm. Last dorsal ray attached by 



