ART. 28 SKULL OF ZARHACHIS FLAGELLATOR KELLOGG S 



Horizon. — The specimen was discovered and excavated by Nor- 

 man H. Boss on December 30, 1923. The jagged extremity of the 

 rostrmn was found protruding from a layer of greenish sandy clay 

 about 8 feet above the beach at a point less than 50 feet from the end 

 of the cliff north of the Boy Scout camp. Shattuck's zones 6-8 are 

 not clearly differentiated at tliis point and the specimen came from 

 one of these three zones. 



SKULL 



Dorsal view. — As mentioned in the preceding paper,^ the arrange- 

 ment of the bones which comprise the dorsal surface of the brain case 

 corresponds in a general way with the skull of the Cliinese porpoise, 

 Lipotes vexillifer, now living in Tung Ting lake and its tributaries. 

 There are a number of rather obvious differences, as, for instance, the 

 development of a high crest on the extremity of each supraorbital 

 process, the projection of the ascending processes of the premaxillae 

 behind the nasals, the presence of a pair of crescentic orifices for 

 nerves on the posterior walls of the "blow holes," the outward curva- 

 ture of the vomerine trougli to form a portion of the dorso-anterior 

 wall of each nasal passage, and the prolongation of the anterior 

 extremity of the zygomatic process and the postorbital projec- 

 tion of the supraorbital process so that they overlap. In its general 

 features, the skull of Zarhachis is characterized cliiefly by the ex- 

 ceedingly long and slender rostrum wliich comprises more than 

 five-sixtlis of the total length of the skull, the "upended" supra- 

 orbital processes of the frontals, and the pair of crescentic orifices on 

 the posterior walls of the nasal passages below the rehatively thick 

 nasals, peculiarities that are most noticeable when contrasted with 

 skulls of other known porpoises. Since the rostrum was fully described 

 in the previous paper, there is no necessity for a detailed discussion 

 of tliis part of the skull. 



All of the brain case posterior to the nasal passages and tlie "up- 

 ended" supraorbital processes was missing from the first skull 

 (Cat. No. 10485, U.S.N.M.). A small fragment of bone which 

 appeared to be a portion of the vertex was found alongside of this 

 skull and it was so placed in the restoration ^ of the brain case. 

 The brain case of the second skull (pi. 1) is in a fair state of preserva- 

 tion and the description that follows has been prepared in the form 

 of a supplement to the preceding paper. 



Behind the antorbital notches, tlie maxillae push back over the 

 frontals and expand into relatively thin horizontal plates. The outer 

 border of each maxilla is deflected obliquely upward and inward to 

 conform with the curvature of the " upended" crestlike portion of the 



« Kellogg, R., A fossil porpoise from the Calvert formation of Maryland. Proo. U. S Nat. Mus., vol. 63, 

 publ. 2482, pp. 1-39, pis. 1-18. March 26, 1924. 

 « Kellogg, R., Idem, pi. 1. 



