440 On the supposed Discovery of a minute Vertebrate Jaw. 



XL VI II. — Note on the supposed "Discovery of an extremely 

 minute Vertebrate Lower Jaw in Mud dredged at St. Helena, 

 by Dr. Wallich, F.L.S." By C. Spence Bate, F.R.S., 

 F.L.S. &c. 



No doubt every naturalist must have received with astonish- 

 ment Dr. Wallich's recent announcement of his discovery of the 

 jaw of so minute a vertebrate animal as he records in the ' Annals ' 

 for October last. 



I am sure he will not think that I am intrusively officious 

 in pointing out some conditions in the specimen that appear to 

 throw considerable doubt upon its being the jaw of any animal 

 at all. 



I would premise that, upon the announcement of any new or 

 important circumstance, it is incumbent that we should first 

 ascertain whether or not it be consistent with our present know- 

 ledge, before the discovery be accepted as a fact. 



Assuming that Dr. Wallich's figure in the ( Annals,' as I have 

 no doubt, is correct, there are two features that seem to be in- 

 consistent with the idea of the specimen being the jaw of a 

 vertebrate animal : I allude to the circumstance of there being 

 no condyloid process, and the character of the teeth. 



I believe that I am correct in asserting that we have not a 

 single instance of an animal having the marginal process of the 

 jaw developed into a serrature such as Dr. Wallich has figured. 

 In those reptiles where the teeth anchylose with the bone, the 

 teeth are yet implanted in alveoli of their own. In fish (of which 

 this cannot be a jaw), the dermal attachments of the teeth, when 

 removed, leave the jaw smooth. 



The question will probably be put, If it be not the jaw of a 

 vertebrate animal, what is it ? In reply, I would state that it 

 appears to me to be the dactylos or last joint of a leg of a small 

 Hyperine Crustacean, and that the circumstance which has misled 

 Dr. Wallich is that, the animal being near the period of moulting 

 its skin, the joint exhibits, within, a second row of marginal 

 armature, which has been mistaken for a second ramus. 



I have repeatedly seen specimens under such conditions as I 

 mention, which, though not agreeing in exact detail of serrature 

 with that figured in the ' Annals/ may yet be sufficiently near 

 to identify the group to which the part belongs. 



In the sketch below, I figure a leg of Phrosina longispina, as 

 well as one in which a drawing of the supposed jaw is sub- 

 stituted for that of the true dactylos, for comparison with 

 Dr. Wallich's drawing. 



The genus Phrosina is very abundant in the tropical and sub- 

 tropical Atlantic Ocean. 



