On the Skull of Pisodus Ovveui. 357 



late, with the median area a little raised; the thorax convex 

 behind the neck, transverse, arched at the sides, anterior 

 angles obtuse, lateral margin narrow, very clearlj punc-. 

 tured, punctures least close on the disk ; the elytra punctate- 

 striate, stri^ deep and well-marked ,• the legs, palpi, and 

 antennae are concolorous with the paler parts of the body. 



Hah. Main island. At Nikko an old tree, rotten as touch- 

 wood and ivy-grown, yielded eight specimens. Single 

 examples were taken fortuitously in other places by beating 

 foliage. 



LIX. — Description of the Skull (^/Pisodus Owetii, «/« Albula- 

 like Fish of the Eocene Period. By A. Smith Woodwaud, 

 F.L.S. 



[Plate XVII.J 



It is now a well-established fact that many types of Tele- 

 ostean fishes have undergone very little change since the 

 Eocene, or even since the latter part of the Cretaceous period. 

 Several well-defined genera seem to date back thus far, and 

 others are represented by forms that differ in but small 

 particulars. Moreover, a few of the most remarkable speciali- 

 zations in piscine skeletal anatomy characterizing the existing 

 fauna are already recognizable in certain closely related 

 Eocene types, and the progress of discovery is continually 

 adding to the number of known examples. A most striking 

 new case has lately been met with by the present writer 

 among the fishes from the London Clay (Lower Eocene), and 

 this forms the subject of the following notes. 



So long ago as 1845 Sir Richard Owen described and 

 figured the tritoral dentition of an unknown fish from the 

 London Clay of the Isle of Sheppey under the name of Pisodus 

 Oweni (ex Agassiz, MS.)*. The original specimen is pre- 

 served in the Museum of tlie Royal College of Surgeons, and 

 exhibits an ovate pavement of small rounded or polygonal 

 teeth firmly fixed in shallow sockets upon a plate of true 

 bone. Appearances suggested to Sir Richard Owen that the 

 fossil had been attached " to another bone of the skull, most 

 probably, as in the Glossodus and Sadis, to a median bone of 

 the hyoid system." Agassiz, who first examined the specimen, 



* R. Owen, ' Odontography,' p. 138, pi. xJvii. fig. 3 (1845). 

 Ann. & Mag. N. Hist. Ser. 6. Vol. xi. 26 



