11. CRANIOMI. 



[. Trigla hirundo. 

 1. SKULL. 



Of the Triglidae I have selccted Trigla hirundo for detaiied descriptions, a short separate 

 description being also given of Trigla lyra. The other members of the family examined are referred 

 to only as they differ markedly from hirundo. 



The dorsal surface of the skull of Trigla hirundo consists of two portions lying at slightly 

 difEerent levels. The higher portion forms by far the larger part of the dorsal surface of the skull, 

 extending from the anterior ends of the nasals to the hind ends of the suprascapulars, and being 

 covered, in the recent State, by a thin cutis only. The deeper portion is small, forms the dorsal sur- 

 face of the anterior end of the snout, and is covered, in the recent state, by the rostral and the dermal 

 and connective tissues that Surround that cartilage. 



The bones that form the larger, higher portion of the dorsal surface are all firmly bound to- 

 gether, and present an even surface everywhere similarly marked with little granulations arranged 

 more or less distinctly in lines or ridges. At its anterior edge this part of the skull projects, eaves- 

 like, above the hind edge of the deeper, anterior portion, this giving to this higher part of the pre- 

 pared skull somewhat the appearance of a carapace, or, to use the expression employed by Gill in 

 his descriptions of Dactylopterus, a ,,bony casque". This casque-like dorsal portion of the skull 

 is somewhat rectangular in general outline, this being more marked in medium-sized than in large 

 specimens. Its anterior and posterior edges are deeply concave, and there are deep, sometimes almost 

 semi-circular incisures for the orbits. The mid-dorsal line is slightly convex, the amount and manner 

 of the convexity varying with the size of the specimen. In niedium-sized specimens the mid-dorsal 

 line is nearly straight from its hind end to the middle of the orbits. Then it curves slightly downward 

 to the anterior end of the orbits, where it again becomes nearly straight, and so continues to its 

 anterior end. In the large specimen used for the drawings, the interorbital portion is, on the con- 

 trary, markedly flat and straight and is joined by slightly round ed angles to the straight anterior 

 and posterior portions of the surface. 



The mid-ventral line of the skull is concave, and has, as the mid-dorsal line has, posterior 

 and anterior portions that are nearly straight and that are separated by an obtuse and rounded angle. 

 The whole skull thus appears bent downward in its anterior half. 



On the anterior portion of the dorsal edge of the orbit there are, in all my medium-sized spec- 

 imens, two backwardly directed spines, but in my two large specimens there is but one spine, a 



Zoologica. Heft (7. 15 



