420 Dr. Johnston's Contributions to the British Fauna. 



from foreign authors. The Linnean species, however, appears, so far 

 as I am able to form an opinion from the account of Fabricius, to be a 

 Phyllodocc, and at all events is certainly distinct from that described 

 above. Of it I have seen only two individuals, and I believe it to be 

 rare. 



The only other species of Lijcoris which I have seen is the Lye. mar- 

 garitacea of Dr. Leach, which is common. The structure of the head, 

 and the number of its parts, are precisely the same in both, and are well 

 and most correctly represented in the figure of the Lye. margaritacea in 

 the Supplement to the Encyclopsedia Britannica. Savigny says that the 

 proboscis is divided into two joints ; a structure which I have not observed. 

 It is short and thick, with two rows of short ferruginous prickles at its 

 base, and two similar prickles on mammillary processes are situated just 

 under the middle lobe of the head. The point is armed vnth two fal- 

 cate, brovm, serrated mandibles, and around these are four distinct 

 patches of prickles, similar to those of the base. The antennae aie, 

 moreover, described as external and internal, the former larger and 

 thicker than the others. Two papillary processes, consisting apparently 

 of three joints, the last of which is small, and arising beneath the head, 

 are obviously thus characterised ; while the internal are two small seta- 

 ceous filaments, which have their origin from the centre of the anterior 

 margin of the head, and are directed forwards. No organs can appa- 

 rently be more distinct : — the papillary are retractile, with a small nipple- 

 like point, and do not arise from the head, but beneath it. During life 

 the animal is constantly pushing them forwards, and again retracting 

 them. Not so with those to which alone I think the name antennae ought 

 to be applied. They are non-retractile, are regularly tapered, and arise 

 from the vertex, and the animal neither does nor can use them like the 

 others. As for that part of the generic character which says " mamilla- 

 *' rum pediformium par primum secundumque in cirros tentaculares 

 " mutata," such a phraseology can only be allowed by those who adopt 

 his theory of the mutation of organs. That doctrine, I am aware, has 

 been received in this country as if it were not an hypothesis, but an in- 

 controvertible law of naturo. It appears to me in a different light, and, 

 after all, if the organs are thus changed, so that they assume different 

 and various forms, and with these changes take up different, perhaps 



