1907.] OF A FKOG OF THE GENUS MEGALOPHRYS. 347 



other genera of Batrachia described above, I am particularly glad 

 to have had the opportunity of dissecting, and to be able to record 

 the appearance of, the muscles of tliis region of the " thorax " in 

 Pelohates fuscus ; for this genus is refei-i-ed by Boulenger to 

 the same family, Pelobatida?, as that which contains Megaloj^hrys. 

 That Boulenger's view is more correct than that of Mivart * and 

 some others, is testified to by the structures of these various 

 muscular arrangements which have been considered in the 

 foregoing pages. The figure (text-fig. 95, p. 334) is a drawing 

 of the interior of the body of a male Pelohates fuscus, with such 

 viscei'a removed as interfere with the proper view of the trans- 

 versalis muscle. It will be noted that that muscle is very 

 extensively developed and that its origin reaches back not only 

 to the ilium, but for some way along that bone, where it overlaps, 

 but hardly conceals, the coccygeo-iliacus. 



The whole of the transversalis muscle in Pelohates is obviously 

 fixed to the oesophagus, in which there is a slight difference from 

 Megalophrys, where the hinder end of the muscle does not appear 

 to reach the oesophagus but to tei'minate upon the ovi ducal 

 membrane. The Pelohates however, as I have mentioned, was a 

 male ; but the corresponding part of the muscle were it present 

 would naturally lie upon the median mesentery. The muscle is, 

 moreover, at first sight rather reduced in size as compared with 

 that of Megalophrys. But a close study shows that this is due to 

 the semilunar excavation of the posterior margin of the same, — 

 that really its origin extends quite as far back as in Megalophrys. 

 Moreover, in both of these Frogs the muscle completely covers 

 and conceals the ilio-costal muscles ; anteriorly a state of affairs 

 which is not found in Rana &c., as is depicted in the accompanying 

 figure (text-fig. 98). In Pelohates the distinction between this 

 muscle and that which is applied to the terminal cervical aponeu- 

 rosis is very marked ; their fibres do not show any continuity 

 anywhere. This muscle — the ventral part of the diaphragm, as 

 Dr. Keith terms it — is better developed in Pelohates than in Rana. 

 There is hardly any membranous portion left. This is plainly 

 shown in the figure. 



I have also examined into the condition of this oesophageal 

 sheet of the transversalis in other genera. In the South American 

 Geratophrys ornata the muscle is easy to see and is disposed rather 

 differently from the muscle in the genera that have been already 

 referred to. It is not extensive as in Megalophrys ; but is, as in 

 Rana, limited to the fore part of the visceral cavity. Instead of 

 forming at its origin at any rate a single continuous sheet of 

 muscle, it is in Geratophrys distinctly divided into three portions. 

 The present is one of the species of the genus which possesses a 

 large dorsal ossification in the cutis, which is fii-mly articulated 

 to the vertebral transverse process, from the sm-face of which the 

 muscles in question arise. The innermost or posterior of the three 



* " The Classification of the Anurous Batrachians," P. Z. S. 1869, p. 290 &c. 



