Fossil Fishes of the Upper Karroo Beds of South Africa. 263 



Though the specimens were in fair preservation, so many very much 

 finer specimens have since then been discovered that it is now 

 possible to add a good deal to Smith- Woodward's description, and 

 also to modify one or two details. 



The finest specimens are believed to have come from near Ficks- 

 burg in the Orange River Colony, and good examples are to be 

 found in most of the South African museums. The finest I have 

 seen are those in the Cape Town collection. 



The majority of specimens measure from 160 to 210 mm. in 

 length. In the example which is 210 mm. long, the body is 42 mm. 

 in depth at the deepest part, and the head measures 48 mm. to the 

 back of the operculum. 



E. Schellwien (10) has recently described a number of specimens 

 from the Orange Eiver Colony, and has shown the more important 

 features of the skull structure. The specimens I have examined 

 confirm most of his observations, but in one or two points I am 

 inclined to differ from him. Schellwien's specimens show one or 

 two features not seen by me in those I have examined, while I am 

 able to add a number of characters not observed by him. 



Almost every detail of the skull is now known except the basi- 

 cranial region. The f rentals are large, and extend from the nasal 

 region to behind the plane passing through the back of the orbit. 

 The back part of the bone is about twice as wide as the middle 

 portion. Behind it is a large oblong parietal. Below the parietal 

 is a slightly narrower squamosal. My specimens do not satis- 

 factorily show the supratemporal region, but Schellwien finds a 

 narrow supratemporal and a post-temporal. 



The opercular bones are very like those of Lepidotus. The oper- 

 culum differs in being relatively considerably wider in its lower half. 

 Inferiorly it joins the subopercular in a manner very similar to that 

 in the better known genus. The subopercular in Semionotus is only 

 about one-third the size of the operculum instead of half as large as 

 in Lepidotus, while the interopercular is less than half the size of 

 that in Lepidotus. In front of these three opercular bones is a 

 narrow curved preopercular, along which there runs a mucous 

 canal. 



In Schellwien's diagrammatic restoration the postorbital seems to 

 me to be rather too small, while the interopercular is much too large. 

 Above the anterior end of the long preopercular is an elongated sub- 

 orbital smaller in size than the postorbital. The portion of the figure 

 dealing with this region is, in my opinion, erroneous. 



I should be inclined to restore the anterior portion of the skull 



