ART. 20 NEW AND IMPERFECTLY KNOWN FISHES GINSBUEG 13 



from nearly all other genera of the family Gobiidae in lacking an 

 interspinal membrane. The families Eleotridae and Gobiidae are now 

 distinguished mainly by the structure of the ventral fins. In the 

 Gobiidae the two ventrals are united medially by an interradial mem- 

 brane, while a shorter membrane nearly always arches across the two 

 fins, being attached to the short lateral ray of each fin and to the base 

 of the fins in front, thus forming a scoop or funnel-shaped structure. 

 In the Eleotridae the two ventrals are closely approximated but not 

 joined together. It is to be noted that the three genera Eleotrica, 

 Gobulus, and Gobiosoma, which otherwise agree in nearly all technical 

 characters and are very similar in general appearance, form a gradated 

 transition from the Eleotridae to the Gobiidae in so far as it relates 

 to the structure of the ventral fins. An even more striking transition 

 between the two families was recently described in the case of some 

 European scaled gobies.^- It is evident that the chief character hith- 

 erto employed in separating the two families is not satisfactory. 

 Moreover, the divergence in the structure of the ventrals apparently 

 occurred independently in widely separated phylogenetic lines. 

 Regan '^ attempts to divide the two families on the basis of osteolog- 

 ical characters also, but since his study is apparently based on very 

 few genera, it is not conclusive. The proper separation of the two 

 families, showing their differences and their limits, still remains to be 

 worked out. 



GOBULUS CRESCENTALIS (Gilbert) 



Figures 2, 3 



Gobiosoma crescentalis Gilbert, Proc. U. S. Nat. Mus., vol. 14, p. 657, 1891 



(Gulf of California, lat. 24° 22' 15" N., long. 110° 19' 15" W.; 7 fathoms). 

 Gobiosoma crescentale Jordan and Evermann, U. S. Nat. Mus. BuU. 47, pt. 3, 



p. 2259, 1898 (erroneously said to have been taken in 79 fathoms). 

 Gobiosoma crescentale Pellegrin, Bull. Mus. Hist. Nat. Paris, vol 7, p. 162, 1901 



(Gulf of California). 

 Gobiosoma crescentale Osburn and Nichols, BuU. Amer. Mus. Nat. Hist., vol. 35, 



p. 175, 1916 (Agua Verde Bay, Gulf of California). 



Diagnosis. — D. 12, A. 11 (same count in three specimens examined) . 

 Greatest depth, 15.3-17 per cent; least depth of caudal peduncle, 9.8- 

 11.2 per cent; head, 27.6-28.6 per cent; ventral, 20.2-21.4 per cent of 

 standard length. Head markedly depressed, flat on top, its lower 

 profile somewhat curved, its depth directly behind eyes 2.5 in its 

 length. Ventral of medium length, 1.7 times in distance from its base 

 to origin of anal. Both nostrils in front of e3^e, one behind the other, 

 ending in short tubules. Three pimplelike projections of skin behind 

 inner margin of upper lip, one below anterior nostril and two near 

 level of lower margin of eye. Inner row of papillae along lower jaw 



» See De Buen, Trab. Inst. EspaBol Oceanogr., no. 5, 1930. 

 "Ann. Mag. Nat. Hist., ser. 8, vol. 8, pp. 729-733, 1911. 



