The Structure of Dinichthys 



171 



described. Therefore all the previously mentioned investigators have not noticed that 

 the ventral shield makes it possible for us to determine the exact breadth of the fish. In 

 reality, the distance between the two extreme corners of both the antero-ventro-lateral 

 plates (Text-figure 61), to which the extreme corner of AL was attached, gives us the 

 maximum breadth of the ventral side of Dinichthys. This measurement is of very great 

 value as it is the only exact measure of the breadth of the fish we know. It helps very 

 much in reconstructing the outline of Dinichthys. 



All the plates in the ventral shield are quite flat and relatively thin. But we have 

 no reason to suppose that they have been strongly deformed and flattened by pressure. 

 It is probable that they were in reality flat. No distinct clefts of other traces of marked 

 deformation, like those in some plates in the dorsal carapace or the head, are to be found here. 

 It is also doubtful whether the ventral shield was strongly curved, as the curving would 

 shorten the distance between its two extreme angles, and thus make the whole carapace 

 narrower, which is very improbable. 



AMV 



AMV, 



Text-figure 56. 

 The antero-ventro-lateral plate shown from the 

 inside. 



ex, exterior margin; gz, grooved zone; rd, ridges; s^, sockets; 

 w, wall around front and side margins. 



Text-figure 57- 

 The antero-ventro-lateral plate figured from the 

 outside. 



«c, exterior margin; rd, ridges; sl{, sockets. 



