198 Mr. Walker on the British Chalcidites. 



size, and even to a certain extent in form, yet a given series 

 of scales from the lateral line, exhibiting a marked difference 

 in structure, would undoubtedly indicate a corresponding se- 

 ries of species or genera. 



That scale, for such I am now disposed to class it, which is 

 represented at No. 13, has given me the most trouble to deci- 

 pher. It has, at first sight, the appearance of a tooth, but it 

 differs from that of a shark, to which, were it a tooth, it would 

 be the most nearly allied by the great length of the fangs. 

 And indeed there are no instances of teeth being thus let into 

 the jaw; for they are either immoveable and to be considered 

 as parts of the bone, or if moveable they are fixed to the skin. 

 The subject in question, I believe to be the triple subcutaneous 

 insertion of a ventral spine or quasi-scale of a fish nearly al- 

 lied to the Diodon orbicularis, or porcupine fish of the present 

 period. This similarity no sooner occurred to me than I im- 

 mediately boiled a small portion of a Diodon in order to sepa- 

 rate the triple-fanged insertion of a spine from its investing 

 cartilage, and the only reason of my not figuring the latter 

 example is the very satisfactory one of there being no differ- 

 ence except that of size to describe. 



I find also with the scales, traces of ribs and fins, small 

 sharp-pointed teeth, and parts of the vertebrae, and in a few in- 

 stances I have found portions of the body with the scales in 

 situ. But here I close this short account of an investigation 

 which no right-minded man will prosecute without directing 

 his thoughts to Him who of old " turned the hard rock into a 

 standing water, and the flint-stone into a springing well." 

 Peckham, October 5, 1838. 



XXV. — Descriptions of British Chalcidites. By Francis Walker, 



F.L.S. 



[Continued from vol. i. p. 454.] 

 Mas. Corpus sublineare, nitens, scitissime squameuni, parce hirtum : ca- 

 put transversum, mediocre, subquadratum, convexum, punctatum, parum ni- 

 tens, latitudine thoracis ; vertex sat latus ; frons abrupte declivis : oculi rae- 

 diocres, subrotundi, non extantes : ocelli 3 triangulum fingentes, medius 

 perparum anteposiius : antennae subfiliformes, latae, pubescentes, thorace vix 

 breviores; articulus l us sublinearis, validus ; 2 US longicyathiformis ; 3 US et 

 sequentes latiores, oblongo-quadrati, usque ad 6 um curtantes ; clava fusi- 

 formis, acuminata, articulo 6° plus dimidio longior vix latior : thorax longi- 

 ovatus, convexus : prothorax transversus, sat bene determinatus, antice an- 



