FOSSIL AND RECENT 



69 



Hollister (1939) added further differences in the morphology of the lateral line 

 scales and these views are endorsed by the present author. However the differences 

 in the caudal anatomy mentioned by Hollister (1939) are not so consistent as that 

 author implied. For instance, Hollister found a caudal fin-ray count of 34-35 in 

 Megalops while that in Tarpon never exceeded 32. Such a difference does not seem 

 apparent in the specimens examined here. Hollister (1939) also stated that the 

 basal tip of the first uroneural extended to the anterior part of the second preural 

 centrum in Megalops whereas that of Tarpon never extended beyond the first preural 

 centrum, a view endorsed by Greenwood (1970a). While this is true of smaller 

 individuals, some large individuals of Tarpon exhibit the same uroneural structure 

 as in Megalops. 



The variability of the neural arches and spines associated with the first two preural 

 centra of M. cyprinoides has been noted by Greenwood (1970a). To these variations 

 may be added two more conditions, the range of such structural variation being 

 summed up in Text-fig. 33. The neural arch structure of Tarpon is more constant 



4 mm 



10mm 



B 



Fig. 34. Megalops cyprinoides (Broussonet). Diagram to illustrate fringing fulcra 

 (stippled) preceding the uppermost principal ray (arrowed). A, a young individual 

 B.M.N. H. 1890.2.26. 187 ; B, an old individual B.M.N. H. 1913.4.7.1. Broken line 

 indicates the limit of the body squamation. 



