34 PEOCEEDINGS OF THE NATIONAL MUSEUM vol.70 



to an unwise extent. Sufficient is not yet known regarding the 

 anatomy of divers forms of cetaceans for the presentation of a con- 

 vincing discussion of this sort, and the present writer shall certainly 

 not attempt to add to the confusion of the subject. 



Lateral hack musculature. — The term transversarii for the two 

 lateral back muscles is open to the objection that it too closely re- 

 sembles the transversalis of the abdominal region. Murie's designa- 

 tion of supra and infracaudalis can not be criticized on the same 

 grounds, but the names are somewhat ambiguous. Although now 

 apparently distinct from the intertransversarii as we usually know 

 them, the two lateral back muscles evidently constitute a specializa- 

 tion of a part of these, and hence will be termed the superior and in- 

 ferior intertransversarii. 



The intei^t7'ansversanus superior is in cross section wedge shaped, 

 and the fibers are not arranged in herring-bone pattern as was the 

 case in Kogia. They originate from the terminations and for a short 

 distance upon the dorsal surface of the transverse processes of the 

 lumbo-caudal vertebrae, the muscle being strongly tendinous only 

 toward the peduncle. At the last rib, progressing craniad, a thin 

 sheet of muscle seems to diverge over the more dorsal part of the 

 thorax, terminating at the fifth, fourth, and third ribs, as shown in 

 Figure 11. This is included as a part of the intertransversarius only 

 because it apparently agrees so well with Schulte's figure and de- 

 scription of Kogia. Due to the condition of the specimens, this could 

 not be dissected to my satisfaction. I am neither convinced that it is 

 really a part of this muscle, although the two seem to be continuous, 

 or that it is not homologous with a serratus posterior ; but the ques- 

 tion must be left unsettled for the present. 



Kogia and Phocaena, are apparently the only cetaceans heretofore 

 dissected which have this expanded thoracic sheet. Schulte also 

 found a slip of the same muscle extending craniad from the first 

 rib to the occiput dorsad of the scalenus dorsalis. That such a slip 

 may have been present in Neonieris as well, but remained undetected 

 because of the partial decomposition of the specimens, can not be 

 denied. The postcostal portion of this muscle seems to be rather 

 uniform in all the genera discussed, save that in Kogia the fibers are 

 arranged in herring-bone pattern. 



The intertransversarius inferior is, throughout its length, a replica 

 of the lumbo-caudal part of its superior neighbor, but it arises from 

 the ventral portions of the teminations of the transverse processes. 

 Craniad, it narrows and ceases at about the last rib. 



Postcostal hypaxial Tnusculature. — The hypaxialis of the lumbo- 

 caudal region is immense, being in transverse section even more 

 massive than the epaxial or supravertebral muscles. The pedun- 



