298 



FISHERY BULLETDSr OF THE FISH AND WILDLIFE SERVICE 



of scales being ctenoid and in some individuals the 

 ctenoid scales being very few. Indeed, if the four 

 specimens of tetrophthahmis described above had 

 been captured on the Atlantic coast, they readily 

 might have been taken to be extreme variants of 

 oilonga in which the ctenoid character of the 

 scales was entirely lost, except for the difference 

 in the position of the two anterior spots. The 

 three large known specimens of tetrophthalirnvs 

 have a somewhat deeper body and longer head 

 and maxillary than average examples of ohlonga 

 of approximately the same size, but the latter 

 species varies considerably in proportional meas- 

 urements of the various parts, and when sufficient 

 numbers are measured the two species very likely 

 will be found to intergrade to a large extent in 

 those respects. This species may readily be dis- 

 tinguished from all other related species on the 

 Pacific coast of North and South America by its 

 distinctive color pattern, 



Liof/lossina fetrophtholmus Gilbert, Proe. U. S. Nat. 

 Mus. 13: 122, 1891 (Albatross Station 3014 and 301(5; Gulf 

 of California, off Tiburon I.). — Jordan and EIveemann, 

 Bull. U. S. Nat. Mus. 47 (3) : 2622, 1898.— Norman. Monogr 

 Flatfl,shes, p. C9, fig. 37, 1934 (based on U.S.N.M. 47268 

 and 47290).— Breder, Bull. Binshaui Ocean. Coll. 2 (3) : 

 3, 1936 (San Francisquito Bay, Gulf of California).— 

 HiYAMA, Marine Fishes of Pacific Coast of Mexico, edited 

 by T. Kumada, p. 59, pi. 92, flg. B, 1937 (Mexico, definite 

 locality not given). 



PSEUDORHOMBUS 



PscudorhomiHS Bleeker. Versl. Med. Akad. Wet. Amster- 

 dam 13: 436, 1862 (genotype J'seudorhombus arsius 

 (Hauiiltou-Buclianau)=iJ/(o<»6tts polyspilos Bleeker by 

 monotypy). 



Pseudorhomhiis is intermediate between Hippo- 

 glossina and Pa)xdkhthifs. It lacks accessory 

 scales like Hippoglossina and has the dorsal origin 

 over the anterior margin of the eye or a little more 

 forward like nearly all species of Paralichthys. 

 The interorbital width and the size of the eye and 

 teeth differ with the species which form the inter- 

 mediate links in a series showing a gradual transi- 

 tion from Flippoglossina to Paralichthys in these 

 three characters. The color pattern is either 

 somewhat like one or like the other of these two 

 genera, or like a combination of the two, depend- 

 ing on the species. The prepeduncular spot is 

 prominent in some species; the other prominent 

 spots on the body are in two longitudinal rows in 



some species. The differences between Pseudo- 

 7'homhus and Hippogloxsina are discussed on page 

 287. As compared with Paralichthys, the species 

 comprised in Pseudorhomitis are generally of 

 smaller size and they have a somewhat different 

 physiognomy. Their general appearance is prob- 

 ably what induced most later authors to maintain 

 the species in a genus distinct from Paralichthys. 

 As far as I could find after a review of the litera- 

 ture, two characters have been proposed, hitherto, 

 for separating Pseudorhombvs from Paralichthys, 

 but neither one is tenable. 



One of these characters was proposed by Jordan 

 and Evermann (Proc. U. S. Nat. Mus. vol. 25. p. 

 365, 1902) who distinguished P.'i«///o?'^ci;HZ>M.s from 

 Paralichthys by the former having an accessory 

 branch of the lateral line and the latter lacking it. 

 These authors were followed by Jordan and Starks 

 (Proc. U. S. Nat. Mus. vol. 31, p. 173, lOOC). by 

 Weber (Siboga Exped., p. 414, 1913), by Norman 

 (Monogr., p. 61, 1934), and probably by other 

 authors who recognized Pseudorhombus as dis- 

 tinct. However, this character apparently does 

 not hold. In the Indo-Pacific species now placed 

 by authors in the genus Pseudorhombv-s the acces- 

 sory branch is usually more clearly marked and 

 better develojied, extending to the dorsal profile, 

 but ill some of those species it apparently fails to 

 reach there (see Nonnan, Monogr., figs. 59, 61, 63, 

 and 65). The American species under considera- 

 tion also have an anterior accessory branch of the 

 lateral line more or less developed, although it 

 generally does not extend to the dorsal profile. It 

 is best developed in caJifomicus, the genotyj^e of 

 Paralichthys, in which species it generally falls 

 short of the dorsal profile, but in individual fish 

 it often plainly extends to the dorsal fin, to the 

 base of the fifth to the seventh ray. It is evident 

 that as far as the accessory branch of tlie lateral 

 line is concerned, the Indo-Pacific species do not 

 differ generically from calif ornious and should 

 be placed in Paralichthys. 



The other character is that used by Regan (Ann. 

 Mag. Nat. Hist., ser. 8, vol. 6, p. 492. 1910) who 

 divides the two genera on the basis of the number 

 of vertebrae, 10 + 24 in Paralichthys and 10 + 27 

 in Pseudorhombns. He does not state how many 

 species nor the number of specimens examined to 

 see wliether this character is subject to individual 

 variation intraspecifically, or to specific differences 



