THE MACKEREL MIDGE. 191 



Specific characters. — Couchia minor. Lesser Mackerel- Midge. Upper jaw 

 the longer : ventrals long (from j to ^th the length of head), and black at their 

 termination; sides silvery.* 



The Gachis argenteolus of Montagu, Wern. Mem. vol. ii. p. 449, must be 

 adverted to in connexion with the present species. By its describer it is stated 

 to be " nearly allied to the three-bearded cod, Gachis Mustela, in most particu- 

 lars ; but the shape of the head and the colour f are essentially difl'erent." It 

 was the striking dissimilarity presented by a comparison of specimens of C. 

 glauca and Mot. quinquecirrata in these very characters, that led me to re- 

 separate them generically ; and consequently the C. glauca and G. argenteolus 

 may, from agreement in these points, be in the first place regarded of the same 

 genus X as here defined. On looking critically to the detailed description of G. 

 argenteolus, and applying it to the authentic specimen of C. glauca, there is, with 

 one exception, such a similarity in every character which may be comprised under 

 form and colour, that I am fully persuaded they constitute but one species. The 

 single discrepancy, like to a specific one, is that of three cirri only being at- 

 tributed to G. argenteolus ; but as it is much more easy to overlook two than to 

 distinguish all the cirri, § I cannot under the circumstances, and at the same time 

 not forgetting Montagu's great accuracy in description, consider this alone a suf- 

 ficient reason for separation. The localities, too, in which only the G. argenteo- 

 lus and C. glauca are hitherto recorded to have occurred, tend further to favour 

 this view ; by Montagu the first-mentioned was obtained on the south coast of 

 Devonshire, where it has not since been observed ; but by Mr. Couch the latter 

 was some time afterwards procured on the adjoining shores of Cornwall. It is 

 in the present communication that the range of this genus is for the first time 

 shown to extend beyond the South-West of England. Finally, with a full belief 

 of the identity of Montagu's and Couch's fishes, although they have hitherto been 

 regarded by naturalists without any specific reference to each other, I would 

 suggest that the name applied by the former author should be retained, and that 

 Couchia argenteola be applied to the species. 



* The absence of cirri is not given as a character, as better vision than mine 

 may yet detect them. 



t The name of Whitebait (Clupea alba), which Montagu mentions as applied 

 to the G. argenteolus by the fishermen, however erroneously, is sufficiently in- 

 dicative of its Clupea-like aspect. 



X Montagu remarks of the G. argenteolus, that " the whole fish is of a silvery 

 resplendence except the back, which is blue, changeable to dark green ;" and 

 that the three-bearded cod he has " taken of all sizes, from the most minute to 

 its full growth of 16 or 17 inches, and never observed it to vary in colour, ex- 

 cept as it grows large it becomes more rufous, and throws out spots, which is 

 never observed till it exceeds 6 or 7 inches, but is invariably rufous-bro%\ii 

 in its infant state." As a general description, this is equally applicable to the 

 five-bearded cod (Mot.quinquecin-ata), of which I have, however, taken spotted 

 examples smaller than has been just noticed. Sj)ecimens now before me of dif- 

 ferent sizes, from 1 j to 5^ inches in length, are of a tolerably uniform brown co- 

 lour on the head, back, sides, and fins, varied only in the larger individuals by 

 yellowish white at the anterior part of the under surface of the body, and in the 

 smaller by the white extending to the lower portion of the opercle, and here, as 

 well as beneath, faintly tinged with silver. 



§ As before stated, cirri could not be detected in any of the Strangford spe- 

 cimens ; lest this should be owing to want of discrimination on my own part, 

 they were submitted to two scientific friends who are well accustomed to the 

 use of the microscope ; but neither could they detect any cirri under it, nor with 

 the aid of a lens : the specimens, it must be remembered, were small. It is 

 only by very close examination that four cirri can be perceived on the upper jaw 

 of the large English C glauca. " Cirri three, two before the nostrils and one on 

 the skin," are Montagu's words, leaving us in doubt on which jaw he perceived 

 the third cirrus. 



