350 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. $5 
HYPHESSOBRYCON RIDDLEI (Meek) 
Hemigrammus riddlei MEEK, in Higenmann and Ogle, Proc. U. S. Nat. Mus., vol. 
33, p. 18, 1907 (Los Castillas, Orinoco system, Venezuela). 
Hyphessobrycon riddlet E1GENMANN, Mem. Mus. Comp. Zool., vol. 48, pt. 2, p. 189; 
pl. 26, fig. 3, pl. 79, fig. 6, 14a, 1918 (Los Castillas). 
» HYPHESSOBRYCON SOVICHTHYS, new species 
Figure 53 
Holotype.—U. S. N. M. No. 121534, a specimen 27 mm. in stand- 
ard length, collected by Leonard P. Schultz, March 11, 1942, in 
Ciénaga del Guanavana, about 10 km. north of Sinamaica, Maracaibo 
Basin, Venezuela. 
Paratypes.—All the following paratypes were collected by Leonard 
P. Schultz (unless otherwise indicated) during 1942 in the Maracaibo 
Basin of Venezuela: 
U.S.N.M. No. 121539, 7 specimens, 18 to 28 mm., taken along with the holo- 
type and bearing same data. 
U.S.N.M. No. 121540, 28 specimens, 26 to 29 mm., from Rio Apén about 
35 km. south of Rosario, February 26. 
U.S.N.M. No. 121536, 14 examples, 22 to 31 mm., from Rio Negro below 
mouth of Rio Yasa, March 2. 
U.S.N.M. No. 121537, an example, 22.5 mm., from the Rio Agua Caliente, 
2 to 3 km. above Lago Maracaibo, May 1. 
U.S.N.M. No. 121585, an example, 27.5 mm., from the Rio Palmar near To- 
tuma, about 100 km. southwest of Maracaibo, February 21. 
U.S.N.M. No. 121542, 7 specimens, 17 to 28.5 mm., from a cafio % km. west 
of Sinamaica, March 11. 
U.S.N.M. No. 121541, 2 specimens, 22 to 26 mm., from Rio Socuy, 3 km. 
above its mouth, February 24. 
U.S.N.M. No. 121538, 37 examples, 10 to 30 mm., from a muddy pool 
tributary to the Rio Gé near Rosario, Venezuela, collectors L. P. Schultz, 
Walter W. Butcher, and B. C. Refshauge, March 8, 1942. 
This species was taken most frequently among aquatic plants in 
quiet waters and in swampy areas. 
Description—Based on the holotype and paratypes listed above, 
the former and one of the latter being carefully measured, and these ~ 
measurements, expressed in hundredths of the standard length, are 
recorded below, first forthe holotype, then for the paratype in paren- 
theses. Standard length in mm. 27 (80.2). 
Length of head 30.8 (28.8); greatest depth of body 33.6 (34.7); 
snout 7.78 (6.62); diameter of eye 11.1 (9.93); least width of interor- 
bital space 11.1 (10.3); postorbital length of head 15.6 (14.6); least 
depth of caudal peduncle 12.6 (11.6); length of caudal peduncle 15.2 
(14.3); length from tip of snout to rear of maxillary 10.4 (9.93); length 
of base of anal fin 25.2 (26.5); length of longest anal ray 18.5 (20.2); 
longest dorsal fin ray 25.9 (28.8); longest pectoral ray 20.7 (22.2); 
longest pelvic ray 18.5 (17.9); length of upper caudal fin lobe 31.5 
(31.5) and of lower caudal fin lobe 33.4 (83.2); distance from snout 
