406 DR W. CARMICHAEL M'lNTOSH ON THE STRUCTURE OF THE 



fication of the Order* rightly places the genus in a special Family, called Gymno- 

 cephalidce, whose chief characteristics as described by him are: — Absence of 

 cephalic fissures ; brain like that of Polia, but the superior ganglion covers the 

 inferior much less, and is advanced in front of it. He bases his statement of 

 the relationship to the Ommatopleans, as it appears to me, on somewhat 

 questionable grounds, for the ganglia are by no means closely allied in form and 

 structure to those of that group. 



ANNELIDA. 



In the following part of the paper T purpose making a few remarks on the 

 structure of some recent additions to the Annelidan fauna of Britain, as well as 

 of a few species believed to be new to science. Many of them have been known 

 to me for years, and, indeed, were figured and described in my MS. long before 

 the appearance of M. de Quatrefages's " Anneles" and Dr A. J. Malmgeen's 

 " Catalogue of Northern Annelids ;" but the publication of these and other recent 

 works on the subject has occasionally anticipated me in nomenclature — a kind 

 of loss, however, which I esteem rather lightly, since so much yet remains to be 

 done in the minute structure of the entire class. 



Amphinome vagans, Leach (?) — Two genera have hitherto represented the 

 British Amphinomea, viz., Euphrosyne and Spinther, and this species introduces 

 with certainty a third. Two very minute specimens (|th of an inch in length), 

 from St Magnus Bay, occurred in an extensive collection made last year (1867) 

 by Mr Gwyn Jeffreys, while dredging in the Shetland seas. The segments 

 numbered in the one twenty-three, and in the other twenty-seven. The head 

 agrees with that of Hipponbe, Aud. and Ed.,| with which genus I at first thought 

 it most closely allied, but the feet are biramous. In these specimens also no 

 caruncle can be observed, the head forming a smooth rounded eminence, from 

 which a subulate antenna projects. No eyes are present. There are two 

 antennae in front of the median at the anterior border of the snout, and two 

 others at a distance behind. The bristles (Plate XV. fig. 1) of the superior and 

 inferior lobes of the feet agree in structure, and consist (i) of a somewhat stout 

 kind (b, c), which has serrations on one side, and thus not observable in all 

 positions ; and (2) of various modifications of a peculiar bifid bristle, some of 

 which («), especially towards the posterior end of the body, show a swollen 

 part below the bifurcation, with a short and simple limb, and a longer process 

 serrated on one side, while others have the serrated limb extremely elongated 

 and tapered to a fine point, and with little or no swelling at the bifurcation. 

 The inferior cirrus is very small. A large specimen from the Channel Islands 

 seems to belong to the same or a closely allied species, but there are sixty-seven 



* Zeitsch. fur wiss. Zool. xii. 1863. 



j- Hist. Nat. du litt., &c. torn. ii. p. 128, pi. ii B. fig. 10. 



