BRITISH NEMERTEANS, AND SOME NEW BRITISH ANNELIDS. 413 



described by the two foregoing authors as distinct species (which I hardly think 

 is the case), and classes them under the genus Kefersteinia. They also appear to 

 me to be in all respects much more nearly allied to the Hesionea than the Syllidea. 

 The Castalia punctata, Mull., again, has a biramous foot, whose compound bristles 

 (Plate XVI. fig. 1) have on the whole a longer terminal portion, with finer 

 serrations than in P.fusca. I have found it on various parts of the British coast. 

 Autolytus pictus, Ehlers* — I agree with Dr R. Greeff,| who, in his remarks on 

 Autolytus prolifer, observes that the above species (the Procercea picta of Ehlers) 

 is, in truth, an Autolytus. It was first found in Britain under a stone in a 

 rock-pool at Paible, North Uist, and again, in greater numbers, at St Andrews. 

 Its length is about an inch. The dorsum is very prettily marked by a pale 

 central band, with numerous and rather regular transverse branches, which, 

 uniting with a pale lateral belt on each side, cut the sepia-brown pigment- 

 masses into oblong spaces. The latter are minutely striated under the lens by 

 fine pale lines, and the intervals dotted by almost microscopic pale grains. The 

 first twelve or thirteen segments are darker in hue dorsally, and the intersecting 

 lines paler; and in some the oblongs are decidedly paler in this region. Below 

 the pale lateral belt, and just above the feet, a dark-brown band runs from end 

 to end, intersected only here and there opposite the pale transverse belts by 

 narrow pale lines. A dark patch of brown is placed behind the median tentacle, 

 and from the latter two characteristic diverging pale lines proceed backwards. 

 The under surface is of a pale whitish or flesh colour. These markings were 

 well seen in specimens preserved for upwards of a year in spirit. The head is 

 rather small, and appears at first sight to be supplied with two eyes only, which 

 are situated laterally, and somewhat in front of the great median tentacle, but a 

 careful examination shows two clear lens-like structures on each side, the larger 

 towards the front of the pigment-mass, and the smaller behind. There is thus 

 some difference between our description and that of Dr Ehlers, since he shows 

 a posterior pair of eyes considerably behind the median tentacle, and quite 

 separated from the compound group in front. This ocular region is richly 

 ciliated, and so is the dark pigmentary portion on the sides immediately behind. 

 The median tentacle had its place supplied in a few instances by two of equal 

 length, but this is simply an abnormality. The segments (upwards of 100 in 

 number) behind the three or four anterior rings are furnished with a rather 

 short dorsal cirrus, a few simple spines, and a fascicle of bristles (Plate XV. fig. 

 11), which possess a short terminal piece, with a bidentate apex. I have not 

 seen any with a tridentate terminal portion, as shown by Dr Ehlers. Towards 

 the tail there is only a single conspicuous spine in each bundle of bristles, and, 

 finally, a larger and smaller spine form the sole appendages to the feet. Here, 



* Die Borstenwiirmer, &c. p. 256, taf. xi. 



f Archiv fur Naturges. 1866, and Annals N. Hist. March, 1868. 

 VOL. XXV. PART II. 5 N 



