170 Prof. M'Intosli's Notes from the 



skin and freely movable witli tlie branchial apparatus. The 

 truncated tip of the basihyal is marked by various hard 

 wrinkles, and it projects from the ventral surface a consider- 

 able distance in profile (PL VI. fio;. 3). When the hyoidean 

 apparatus is pushed forward the blunt tip has a tendency to 

 close the aperture. 



Viewed internally (PI. VI. fig. 2) the basihyal is depressed, 

 much of it passing into the aperture in the floor of the mouth 

 and projecting ventrally. The ceratohyals are nearly normal 

 or only very slightly lowered. In the fresh specimen the 

 movements of the parts were quite free, as in an ordinary 

 example, and apparently prehension and deglutition were 

 unimpaired. 



So far as observation goes, it would seem that the fish had at 

 one time been captured by a powerful siiark-hook which had 

 struck it from below and pierced the basihyal and the soft parts 

 near it. In its struggles it probably wrenched the tip of the 

 basihyal,VFhich,\vith the soft parts, gave way under the powerful 

 strain, so that about 2 inches of the basihyal with the tip of 

 the tongue were lost and a large gap externally was caused. 

 Whether tlie hook remained a short or a long time in the wound 

 would depend on the soundnessof the tackle. Though the whole 

 hyoidean apparatus must have received a considerable wrench, 

 yet the healing and contraction of the wound and the cicatri- 

 zation of the coverings of the depressed basihyal have been 

 so complete that comparatively little inconvenience has 

 resulted. The large ventral aperture would take in water, 

 whilst the plug of the basihyal would prevent the loss of 

 food. Moreover, swallowing would not be interfered with. 

 The slender gill-nets prove more deadly to such a powerful 

 fish than a hook, for they yield on every side, and, though 

 torn, soon envelop fins and tail and impede branchial respira- 

 tion. On the other hand, it is compaiatively rare for such a 

 form to envelop itself with the lines, from which this shark 

 is an adept at picking off the fishes after they are hooked. 



As indicated elsewhere, the porbeagle shark has never been 

 known to attack the human subject, yet the great muscular 

 power and weight of an example measuring 9 feet and the 

 length and sharpness of its teeth undoubtedly fit it for any 

 predatory function. If by chance it acquired such a habit, 

 and was as common in Bt. Andrews Bay in the warmer 

 months as it is in the cold, those who swim in the inshore 

 waters would have to face a new danger. 



