340 MEMOIRS OF THE CARNEGIE MUSEUM. 



among the specimens belonging to the Bayet Collection, and are shown in the 

 accompanying plates (Cat. Nos. 5320 and 5329). Most of the structural details 

 are displayed in the larger of these to better advantage than in any other specimen 

 which has come under the observation of the writer. 



Genus Dules. 

 This recent genus is represented in the Upper Eocene fish-fauna of Monte 

 Bolca by a single species, D. temno'pterus Agassiz, of which but few examples are 

 known. None are preserved in the British Museum; only one (the original holo- 

 type) in the Paris Museum, and but three in the Carnegie Museum. These last- 

 mentioned examples are cataloged as Nos. 4297, 5316+6315a and 5324. They 

 are all smaller than the holotype and are evidently immature, but well preserved. 

 Agassiz's description of this species is to be found in volume IV, p. 91, of his Re- 

 cherches sur les Poissons Fossiles, 1836. 



Suborder Scombroidei. 

 Maxillaries more or less firmly attached to the non-protractile premaxillaries, 

 which are typically produced and pointed anteriorly. Cranium with the orbito- 

 rostral portion elongate and the postorbital portion abbreviate; parietals separated 

 by the supra-occipital; no orbitosphenoid; basisphenoid present; pro-otics giving 

 rise to an osseous roof for the myodome. Vertebral column of solid centra which 

 are co-ossified with the arches. Pectoral arch attached to the cranium by a forked 

 post-temporal; no mesocoracoid; pterygials more or less regularly hourglass- 

 shaped, four in number, three of them attached to the scapula. Pelvic fins of a 

 spine and five soft rays or variously reduced, thoracic or subthoracic in position, 

 the pelvic bones attached to the clavicles. 



Division Xiphiiformes. 



Hypural nearly or quite hidden by the bases of the caudal fin-rays. A long 



pointed rostrum, formed by the united premaxillaries and by the nasals, the latter 



meeting in front of the ethmoid and then diverging and tapering forward. Mouth 



with lateral cleft; teeth small or absent. Epi-otics separated by the supra-occipital. 



Pectoral fins placed low. 



Family Blochiid^. 



Vertebral column consisting of twenty-four vertebrae. Pelvic fins absent. 

 Neural and haemal spines not expanded. Ribs apparently sessile. Body covered 

 with slightly imbricated, diamond-shaped, bony scutes; two longitudinal series of 

 enlarged scutes on each side. 



