508 PROCEEDINGS OF THE NATIONAL MUSEUM vol.86 



MACROPINNIDAE, new family 



Diagnosis. — Stomiatoid fishes with an adipose fin. The ventral 

 fins are abdominal, situated on the side of the body above the ventral 

 outline, and with very elongate rays, reaching to, or beyond, the base 

 of the caudal. The anal fin is normal as long as or longer than the 

 dorsal, and well separated from the caudal fin. The anus opens some- 

 what ahead of the origin of the anal. The ventral surface is nomially 

 rounded. There is no flat ventral "sole," with an anterior projection 

 below the head. The eyes are cylindrical, pointing directly upward. 

 They are covered with dense black pigment laterally and anteriorly so 

 that vision can be only vertical. The maxHlaries are present, broadly 

 expanded posteriorly. The gape is minute. The opercle is small 

 and ovoid, with its longest diameter only a little more than its short- 

 est. It does not project below the level of the pectoral base. The sub- 

 opercle is only a little smaller than the opercle and is of the same 

 general shape. The body is short and stubby; the head is large. 

 There are no luminous spots on the body or head. There is no men- 

 tal barbel. 



This family of peculiar fishes appears to be somewhat related to the 

 Opisthoproctidae, which are found in the eastern Atlantic (Vaillant, 

 1888; Zugmeyer, 1911a and b; and Roule and Angel, 1933) ; the western 

 Atlantic (Gregory, 1933); and the western Pacific in the South China 

 Sea (Trewavas, 1933). No fish remotely resembling the present 

 species has been described from the eastern Pacific. From the 

 Opisthoproctidae they differ strilvingly in the presence of a maxillary 

 (absent in the Opisthoproctidae), which is broadly expanded poste- 

 riorly; by the perfectly normal anal fin, which is larger than the dorsal, 

 and the normally placed anus (in the Opisthoproctidae the anus opens 

 posteriorly near the base of the caudal fin; the anal fin is normally 

 atrophied, and is either very small and only slightly separated from 

 the caudal or is so closely appressed to the latter that it appears to be 

 absent); by the differences in the size and shape of the opercle and 

 subopercle (the Opisthoproctidae have the opercle long and narrow; 

 the subopercle is very small and is almost hidden by the preopercle) ; 

 by the lack of a ventral "sole" (this peculiar structure, characteristic 

 of the Opisthoproctidae, consists of a flattened ventral surface which 

 projects more or less beyond the normal outline under the head and is 

 supported by the anterior arm of the cleithrum); by the position and 

 extreme length of the ventral and pectoral fins (in the Opisthoproctidae 

 the ventral fins project into the ventral outline and are of normal 

 length); and by numerous other peculiarities (see Trewavas, 1933). 

 The Macropinnidae, however, resemble the Opisthoproctidae in the 

 small gape, the general shape of the body, the presence of an adipose 

 fin, and the dorsally directed eyes. 



