492 DR. W. G. RIDEWOOD ON THE CRANIAL [Dec. 13, 



Fregatte Novara, Zool. i. 1869, Fisclie ; Cope, Trans. Amer. Pliil. 

 Soc. n. s. xiv. 1871, p. 455 ; Gill, I. c. p. 17; Smith Woodward, 

 Brit. Mus. Cat. Foss. Fishes, iv. 1901). Their justification appears 

 to lie mainly in the fact that Cliiroceidras possesses in its intestine a 

 spiral valve which is not present in Clupea and its allies (Valen- 

 ciennes, I. c. p. 160 and pi. 565), in the absence of ca;ca (^ibid. 

 p. 162), uiid in the pi-esence of a pseudobranch in Chirocentriis 

 and its absence from most Clupeoids (Miiller, Abhandl. Akad. 

 Wiss. Berhn, 1844 (1846), p. 191). The only craniological 

 difi'ei-ences worth mentioning are the considei'able depth of the 

 posterior temporal groove of Chirocentras, the small size of the 

 orbitosphenoid, the firm union between the premaxilla and maxilla 

 (Valenciennes, I. c. pp. 150, 152, and 154), the more or less com- 

 plete concealment of the symplectic (Boulenger, Ann. Mag. Nat. 

 Hist. (7) xiii. 1904, p. 164), the bony nature of the first pharyngo- 

 branchial, and the absence of a spicular bone. The value of the 

 evidence of the last two items is certain!}^ not great, for except 

 when (as in Elops) both ossified first pharyngobranchial and 

 spicular bones are present, it is not possible to deny absolutely that 

 what appears to be the first pharyngobranchial bone is not the 

 spicular bone which has become shortened and thickened and more 

 forwai'dly directed than usual. 



The resemblances existing between the skeleton of Chiroceniru,s 

 and that of such extinct forms as Porth&as, Ichthi/odectes, and 

 jSaurodon, which attained their maximum development in Creta- 

 ceous times, suggest that the formei- genus is a sui-vival of an 

 ancient type (see Smith Woodward, I. c. p. vii) ; but the teeth of 

 the existing C'hirocentrus are not lodged in distinct sockets as are 

 those of the Saurodontida\ 



As regards Chanos, the evidence of the skull favours the view 

 of separating the genus fi-om the Clupeidte, and of according it a 

 family rank. Chanos has expeiienced a variety of treatment at 

 the hands of taxonomists. It was first regarded as a species of 

 Magil (Forskal, Desc. Anim. 1775, p. 74; Gmelin, Syst. Nat. 

 Linn. i. 3, 1788, p. 1398), and later as a species of Leaciscus (Gray 

 and Richardson, Diefienbach's 'Travels in New Zealand,' 1843, 

 ii. p. 218). Valenciennes (Hist. Nat. Poiss. xix. 1846) placed it 

 with Gonorhynchas Jtinong the '' Malacopterygiens intermediaii-es 

 entre les Brochets et les Olupes." Glinther (Brit. Mus. Cat. Fishes, 

 vii. 1868) placed it in a group " Chanina" of the family Clupeida-, 

 and Kner (Reise der Fregatte Novara, Zool. i. 1869, Fische), Cope 

 (Trans. Amer. Phil. Soc. n. s. xiv. 1871, p. 455), and Gill (Smith- 

 son. Miscell. Coll. No. 247, 1872, p. 17) separated it from the 

 Clupeidai and placed it in a family of its own. 



The inclusion of Chanos within the family Albulidje, a step 

 which has commended itself to so experienced an ichthyologist as 

 Smith Woodward (Brit. Mus. Cat. Foss. Fishes, iv. pp. 60 and 

 64), is justified in so far as the posterior temporal fossteare roofed 

 over, which is not the case in any other Clupeoid fishes, and in the 

 presence of a well-marked lateral tempoi'al groove, partially roofed 



