510 PROCEEDINGS OF THE NATIONAL MUSEUM vol.86 



sliield bears a dorsal projection which cuts off the Ught coming from 

 ahead. The region of the head immediately anterior to the eyes is 

 transparent, except for a slight amount of pigment around the open- 

 ings of the nostrils, which are placed here. The adductor man- 

 dibularis, the eye muscles, and the ramifications of the cranial nerves 

 are plainly visible. 



The gape is extremely small, not reaching more than a third of 

 the way to the eye. No teeth can be seen on any of the bones of the 

 mouth, although there may be a few minute teeth on the premaxil- 

 laries and the dentaries. The specimens remained in formalin until 

 the osseous structures became flabby. The maxillary is short but 

 greatly expanded posteriorly so that it is nearly as broad as it is long. 



Figure 59. — Macropinna microitoma, new genus and species: Holotype (U.S.N.M. no. 108143), 39.5 mm 



long, from station 621C. 



The dentary is even more expanded posteriorly than the maxillary. 

 This expanded portion fits in under the maxillary, between that bone 

 and the palatine. 



The opercle is oval, with the longest diameter vertical. It is a 

 proportionately small bono. It does not extend below the base of 

 the pectoral fin. The subopercle is a small oval bone about the size 

 of the opercle. The dorsal arm of the preopercle is normal, but the 

 ventral arm is enormously expanded ventrally and is the largest bone 

 in the opercular series. The interopercle is also large and expanded 

 ventrally. It is mostly overlain by the preopercle. It does not reach 

 to the subopercle. The four branchiostegal rays are broad and very 

 thin. The gill rakers are short, broad, triangular, and thin; the gill 

 membranes are broadly united and attached to the isthmus with a 

 broad free fold behind. 



The dorsal and anal fins are similar to each other; the former is 

 inserted a little ahead of the latter. The adipose is situated on the 

 caudal peduncle about midway between the end of the dorsal and the 

 first rays of the caudal. The pectoral fins are large and are situated 



