2ao PAPERS FROM TORTUGAS LABORATORY vol. xxxiv 



has 5. In G. mystacinus the scales in series between gill opening and base of 

 caudal are about 95; scales in lateral line about 59. Although few scales remain 

 on either specimen of O. lonchurus, it is possible to recognize about 57 in the 

 lateral line. Beyond its end, counting is difficult, but a total of 88 may be made 

 out. The number of fin rays and scales in lateral line and the total number of 

 transverse series in the two nominal species are, therefore, almost or quite the 

 same. The supplemental bone of the maxillary, which is variable in this family, 

 in these fish is the same in shape and position. W. H. L. 



The Tortugas specimen has faded to a light brown. The fins are paler than the 

 body, and both dorsal and anal are darker toward their margins. 

 Gulf of Mexico off Florida, in rather deep water. S. F. H. 



Opisthognathus fasciatum Longley 



Opisthognathus fasciatum Longley, in Longley and Hildebrand, Carnegie Inst. Wash. 

 Pub. 517, 1940, p. 259, fig. 18- — Tortugas, Florida. 



Opisthognathus maxillosus Poey 



Although noticed elsewhere, this fish is most commonly, though always 

 sparsely, distributed over the Loggerhead reef, where it lives in burrows. Its 

 burrows most abound about coral stacks just beyond the Thalassia zone. Those 

 of the largest fish are about 40 mm. in diameter and may be more than 300 mm. 

 deep, and terminate below in a chamber having the capacity of a pint measure. 

 The vertical shaft is lined with shell and coral fragments, like that of Opisthog- 

 nathus aurifrons. The proportions of shaft and chamber were learned by filling 

 them with plaster of Paris and digging up the casts after the material had set. 



The mouth of the burrow of O. maxillosus is sometimes surrounded by pieces 

 of dead coral, heaped up in the form of a low cone. Within this rampart the fish 

 then "stands" vertically with little more than snout exposed, keeping a watchful 

 eye on all that comes near. It interrupts its vigil occasionally by trips to the 

 depths, from which it may return with a mouthful of sand to be cast out. Few 

 were found engaged in constructing burrows. Renovation was promptly made, 

 however, when sand was poured into their quarters. At intervals the watch 

 ceases, and a period of complete seclusion begins. At such times the entrance to 

 the shelter usually is closed by the retiring fish drawing in from without a piece 

 of coral that sticks fast. 



Sometimes slabs of coral through which the mussel Lithophagus has bored its 

 way, or other openings, give the fish access to spaces beneath. In one instance 

 several fish had discovered a flat expanse and had occupied ready-made chambers 

 that needed only to be cleared out. They surrounded their doorways, however, 

 with circles of Acropora fragments. 



It is fortunate that the original description of this species serves to identify it, 

 since the type is apparently lost. At Tortugas we have had many specimens 48 

 to 145 mm. long. 



In a series of 8 specimens all had D. XI, 16; A. Ill, 15 in 1, II, 16 in 3, and III, 16 



