78 



BAT,.T-:>IIDJ.. 



Yet I thiuk it is so important that we should avail ourselves of 

 every assistance in determining the species of these animals which 

 are so difficult to observe, that one must run the risk of making 

 such a mistake, as it can easily, be corrected when the opportunity 

 occurs to some competent naturalist to examine a specimen containing 

 both the baleen and the ear-bones. 



The tympanic bones are often found fossil. Professor Owen, in 

 the ' Hist. Brit. Fossil Mammals,' has named and figured the car- 

 bones of the genus Balcena which have been observed in the Crag ; ho 

 has named them as if he regarded the following as distinct species : — 

 1. Balmia ajjinh, fig. 221 ; 2. B. de/inlfa, fig. 222; 3. B. gihhosa, 

 fig. 223 ; 4. B. emanji nata , fig. 224. These bones are all very im- 

 perfect, and the figures of the two latter are not sufficient even to 

 decide whether they belong to the genus Balama or to Fhi/salvs. 

 They differ in the recent genera, thus : — 



Tympanic bone rhombic ; apertixre oblong, only slightly contracted 

 at the iipper end, and about two-thirds of the length of the 

 bone. BAi^iiNA, Eubal.t:na, and Hunterius. 



Tympanic bone irregular rhombic ; aperture irregular, much con- 

 tracted at the upper end, and the wide part not half the length 

 of the bone. Caperea. 



" Dans les galeries d'anatomie comparce du Museum de Paris parmi 

 les preijarations des os d'oreille nous avons trouve dans un meme 

 cadre une caisse tj'mpanique de Balcena Mysticetus, une autre de 

 Balcena australis, une de Pierohalcena communis, et une de Pfero- 

 halama cfigas." — Van Beneden, in Mem. Acad. Hoy. de Bru.velles,18Gl, 

 xxxii. 38. 



Synopsis of the G-eneba. 



I. Atlas united icith the other cervical vertcbrce into one mass ; the lateral 



jjrocess of the axis small, broad, solid. 



A. lialccn thin, polished, tcith a thick enamel coat and a Jine fringe. 



1. Bal^na. First rib slender near, and undivided at the vertebral end. 



Tympanic bone square ; aperture nearly as long as the bone. 



B. JBalecn thick, not jjolishcd, with a thin enamel coat and a coarse thick 



frinije. 



2. EuBALiENA. First rib broad at the vertebral end. Tympanic bone 



square ; aperture nearly as long as the bone. 



3. IIuNTERius. First rib broad, with a double head at the vertebral end. 



Tympanic bone square ; aperture nearly as long as the bone. 



4. Cai>erea. First rib ? Baleen ? Tympanic bone irregular 



rhombic ; aperture irregular, nuich contracted at the upper end, and 

 the wide part not half the length of the bone. 



II. Atlas free from the other cervical vertehrce, which are united info a 



single tnass ; the lateral j)rocess of the avis rounded. 



5. Maclkayius. The lateral process of the axis truncated. 



G. ? PALiEOCETUS. The lateral process of the axis produced, rounded, 

 slightly perforated. 



