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2. INFRAORBITAL BONES. 



The infraorbital bones are all marked witli graniilated surface Striae, and there were, in the 

 two large specimens, but three of these bones. In all of the several smaller specimens there were 

 four bones, the first and second bones of the series, found fused in the larger specimens, here being 

 separate and distinct. Trigla hirundo thus differs in the number of its infraorbital bones from any 

 of the combinations given by Günther in his descriptions of the fishes of the family, that author giving 

 five of these bones in Trigla pini, two in Trigla gurnardus and six in Trigla lyra. But these numbers, 

 given by Günther, niay not be correct for all ages of the fishes mentioned, for in two specimens of 

 T. gurnardus sent me by Dr. Allen, of Plymouth, England, there were five infraorbital bones instead 

 of two as stated by Günther. 



The anterior bone of the series, in the smaller specimens of Trigla hirundo, is the lachrymal, 

 and is a large and somewhat triangulär bone, the anterior end of which curves strongly mesially 

 and so gives to the bone a concave internal and convex external surface. The curved anterior end of 

 the bone is considerably thickened, but its ventro-anterior edge is simply coarsely serrated and not 

 furnished with prominent spmes, as Günther states in his descriptions of this fish. In this the fish 

 resembles Günther's descriptions of Trigla gurnardus rather than T. hirundo, its colour and other 

 characteristics however identifying it as the latter. The thickening of this anterior end of the lach- 

 rymal is apparently due to accretions to its inner surface, and this surface of this part of the bone 

 is partly covered with surface Striae or granulations. From the bind end of this thickened portion, 

 two ridges run backward on the internal surface of the bone; one along the ventral edge of the bone, 

 and the other near and parallel to its dorso-anterior edge; both ridges being prolonged beyond the 

 body of the bone as relatively long and slender processes. The dorso-anterior edge of the bone, dorso- 

 anterior to the second one of the two ridges just above mentioned, is thin, and its anterior and posterior 

 thirds rest upon and are firmly bound to portions of the dorsal edge of the palatine. Between these 

 two regions of contact with the palatine, the lachrymal is cut away by a long oval incisure which 

 is bridged by the underlying palatine. An opening is thus left between the lachrj^mal and the palatine, 

 this opening lying directly opposite the slit-like opening of the nasal pit and lodging the lateral half 

 of the nasal sac. That part of this edge of the lachrymal that lies anterior to this nasal incisure rests 

 upon the maxillary process of the palatine, and there has a flat, pointed, and more or less developed 

 process which, as stated when describing the nasal, gives sliding articulation to the antero-lateral corner 

 of that bone. That part of the edge of the lachrymal that lies posterior to the nasal incisure inchnes 

 mesially and rests upon those portions of the palatine bone and cartilage that form the posterior ethmoid 

 process. On the external surface of this part of this edge of the lachrymal there is a small groove, 

 parallel to the edge and extending posteriorly to the base of the slender and related dorso-posterior 

 process of the bone. At its anterior end this groove is bounded mesially by a part of the palatine, 

 and here, and throughout the larger part of its length, the groove is, in large specimens, filled with 

 a line of tough fibrous tissue which binds the bone to the summit of the articular ridge on the ventral 

 surface of the ectethmoid. There is thus articulation here between these two structures, but there 

 are no regulär articular surfaces. The articulation, such as it is, represents the combined ethmo- 

 lachrymal and posterior ethmo-palatine articulations. Posterior to this articular portion, the dorso- 

 posterior process of the lachrymal projects backward as a free and slender process which lies against 

 and is closely attached to the larger one of the two ethmo-palatine ligaments already described. This 



