MICRURA FASCIOLATA. 197 



dorsally and ventrally, and furnished with a pale caudal filament. It is frequently marked by 

 transverse lines or slight furrows. 



Colour. — Pale skin, ash or brownish ; dorsum speckled with pale brown touches, especially 

 distinct over the head, which has also a well-marked reddish hue in the ganglionic region. A little 

 within the pale margin of the body a pinkish streak occurs on each side from the coloration of the 

 nerve-trunks. Posteriorly the lateral divisions of the dull yellowish digestive tract shine through 

 the skin. Ventral surface of a pale skin-colour, also enlivened by the coloration of the nerves, 

 and in some cases with a few pale brownish specks anteriorly. The caudal style occasionally 

 shows a few white grains in the central line towards the base. 



Head. — Spathulate, but much pointed towards the tip, dilating from the latter backwards to 

 the termination of the cephalic fissures, the whole region being peculiarly hastate. Eyes small, 

 black, grouped on each side of the pointed snout, and varying in number from four to eight 

 on each side. The lateral fissures are deep, and have the reddish hue very brightly marked 

 posteriorly. 



This is one of the flattest among the shorter species of the group, both before and after 

 preservation in spirit. During life it swims through the water on its edge, with an eel-like 

 wriggle, similar to that of A. pitcher, but somewhat less vigorously. When progressing the 

 margins of the body are often very prettily frilled, the reddish longitudinal lines just within the 

 pale border increasing the effect. It is rather irritable, throwing out its yellowish proboscis 

 when touched, or breaking into several fragments. The former clings closely to the finger by 

 means of its tenacious secretion. 



It fixes the tip of its caudal process as in M. fasciolata, and elongates it so as to resemble a 

 very fine thread, which, however, is slightly moniliform. It agrees in minute structure with the 

 foregoing, and, when detached from the worm, much resembles a long Opalina, or other ciliated 

 organism, in facile and independent movements. 



The skin presents an acid reaction to test-paper. 



I at first thought that this form was only a small variety of the great Gordius fragilis of 

 Daly ell (the previous species), and future investigators may establish a closer relation between 

 them than I have been able to make out. I did not feel justified, however, in uniting them, on 

 account of the remarkable difference in the structure of the proboscis, which in M.fusca has the 

 anatomy characteristic of Lineus, while the double isolated longitudinal bands at one of the poles 

 in transverse sections of the organ in C. angulatus exhibit quite a new feature. 



No author, so far as I am aware, has mentioned the caudal process in the last species, but 

 this is a point which may have been easily overlooked. 



Whether the young animal shown in Plate VI, fig. 4, is an early condition of this or an 

 allied species I am unable to decide. It was one of the novelties found by its artist during one 

 of her trips to St. Andrews in the spring of 1866. 



2. Micrura fasciolata, Mrenberg. Plate VI, fig. 2. 



Specific character. — Eyes marginal, placed towards the anterior part of the snout. Body 

 various shades of brown, generally barred with white belts. 



