04 Mr. C. T. Re£ran on 



o' 



XI r. — Xotes on same Loricar'iid Fislies, iv'ith Descriptions of 

 Two new Species. By C. Tate Regan, B.A. 



Tx my monog:raph of the Loricariiclfe I followed Steindachner 

 in placing Plecostomus horridus, Kuer, in the synonymy of 

 P. emnryinatus, Cuv. & Val., and Eigenmann in uniting 

 P. tennicaitda, Steind., to the same species. Althongh I 

 liave never seen specimens of the first-named, I am now of 

 the opinion that it is prohahly distinct from P. emarginatus, 

 ■whilst I am quite sure that P. tenuicauda should be recog- 

 nized as a valid species. P. horridus docs not seem to have 

 the deeply emarginate caudal fin with produced lobes which 

 is so characteristic of the other two species, whilst P. tenui- 

 cauda may at once be separated from P. emanjinatus by the 

 greater length of the base of the dorsal fin. The following 

 description is based on three specimens, from 200 to 380 mm. 

 in total length, from Baranquilla, Colombia. 



Plecostomus tenuicauda. 



Pleeostomvs tenuicauda^ Steind. Denkschr. Ak. Wien, xxxix. 1878, 



p. 40, pi. vi., and xlii. 1880, p. 6^. 

 Plecostomus euiari/iiiatus {T^».xt.),YA'^mm. & Eigenm. Occ. Pap. Cal. 



Ac. i. 1890, p. 400 ; Pu'g-an, Trans. Zool. Soc. xvii. 1904, p. 210. 



Depth of body 5-6 in the length, length of head 3|-3|. 

 Depth of head I5-I3 iu its length, breadth of head Ig-le* 

 length of snout 1^-2, diameter of eye 6-8], interorbital 

 width 21-2;\. Length of mandibular ramus 3-3^ in the 

 interorbital width ; rami of both jaws subequal, wdth 24-32 

 teeth on each side. Barbel 1^-1 § the diameter of eye. 

 Snout narrowed anteriorly ; supraorbital edges not or scarcely 

 raised; opercular bones without marginal bristles ; temporal 

 plate not distinctly carinate ; supraoccipital with strong 

 median ridge extending posteriorly on to the well-developed 

 pointed occipital process, which is bordered on each side by 

 a lateral scute or pair of scutes and at the apex by a median 

 scute. Scutes spinulose, the posterior ones usually weakly 

 carinate, 28-29 iu a longitudinal series, 8 between dorsal 

 and adipose fin, 14-15 between anal and caudal. Lower 

 surface of head and abdomen almost completely covered with 

 small granular scales. Dorsal I 7, the first ray as long as 

 the head, when laid back extending to the third or fourth 

 scute behind the last ray, which is ^| as long. Length of 

 base of dorsal equal to or a little greater than its distance 

 from the adipose fin, which is well developed. Anal I 4. 



