150 PEOF. OWEN ON NEW AND EAEE CEPHALOPODA. 



The mandibular, radular, and salivary organs are almost in miniature what is shown 

 ill the same apparatus of the large Cephalopod next to be described, and justify the 

 reference of the Hunterian specimen no. 308 to the following genus and species : — 



Genus Enoploteuthis, d'Orb. i 

 Species Enoploteuthis Cookii, Ow. 



The beak (PI. XXX. figs. 1, 2, 3) consists, as in all Cephalopods, of an upper (fig. 1) 

 and a lower (fig. 3) mandible ; and, as in all the Dibranchiate kinds, the hardest part 

 does not exceed the density of horn. In each mandible may be distinguished an 

 anterior exposed, or " rostral " part {a b e f), and a posterior concealed part [d g), which, 

 as affording attachment to the biting-muscles, may be termed " apophysial." This is 

 the part in which the corneous density degenerates into a kind of gristly flexible tissue. 



As in all Cephalopods, the lower mandible receives the upper when the beak is 

 closed. 



The rostral part of the upper mandible (fig. 1) sends forward a long, somewhat 

 slender, decurved, sharp-pointed " uncus," a, 11 lines (=23 millims.) in length at the 

 lower border, as defined by the " ala." This part, b, descends vertically with a feebly 

 convex anterior border to apply itself to the inner surface of the corresponding part of 

 the lower mandible (fig. 3, /). The upper border of the " uncus " is continued backward, 

 in a convex curve, 3 inches from the apex. The hind border, c, of the rostrum has an 

 extent in a straight line of 2^ inches ; it describes a sigmoid curve concave forward in 

 the upper three fourths, convex below, both curves feeble. The " apophysis," d, d, is 

 continued d^ inches behind the rostrum. Its upper part begins 9 lines (:=20 millims.) 

 belcnv the hind and upper apex of the rostrum ; the lower border quits the rostrum 

 much nearer the lower apex of the ala, b. Much of the interior border of the apophysis 

 becomes free very near the hind border of the rostrum, c, leaving a long but shallow 

 groove for the tendinous insertion of the supramandibular muscle ; but a ridge-like 

 extension continues the under or oral surface of the rostrum backwards, forming a horny 

 roof of the fore part of the mouth, the extent of which is shown in the vertical section 

 given in fig. 1, PL XXXI. The apophysial plate expands vertically as it retrogrades 

 to its mid extent, PI. XXX. fig. 1, d, d, where the vertical diameter is 2^ inches ; it 

 then contracts, describing a sigmoid curve to the upper apex. The whole length, in a 

 straight line, of the upper mandible is 4f inches. The extent of the hinder cartila- 

 ginous border is from 2 to 3 lines, as indicated by the dotted outline in fig. 1. 



The lower mandible (ib. fig. 3) has a smaller apophysis and a shorter but deeper 

 and rather less sharply pointed uncus, e (PI. XXX. figs. 2 & 3). From the base of the 

 uncus is continued a broad ala, f, overlapping the corresponding part, b, of the upper 



' Histoixe Naturelle des Cc'phalopodcs Acctabulifures, p. 336. 



