Mr. C. CoUingwood o?i Nudibranchiate Mollusca. 463 



the three-cornered spicula so characteristic of D, aspei^a. Doris 

 proxima is scattered in considerable numbers all along the 

 Cheshire shore of the Mersey estuary, from Monk's Ferry to 

 New Brighton, but is nowhere very abundant. It is usually 

 about half an inch long, though sometimes met with very minute, 

 and varies in colour from white to various shades of yellow and 

 orange. It spawns early in March. I do not think the Doris 

 aspera is found here, and have hitherto searched for it in vain. 

 It appears to be replaced by this allied species. 



Doris bilamellata. — This is perhaps the most common Nudi- 

 branch in our estuary, and may be found in the utmost pro- 

 fusion, especially in early spring, its chief spawning season being 

 in February and March. At that period the stony ground beside 

 Egremont, and that in the neighbourhood of the railway pier at 

 Monk's Ferry, literally swarm with this species, and are spotted 

 in all directions with the white ribands of spawn. These two 

 localities are separated by a distance of about 2^ miles, the latter 

 being most distant from the sea; and a considerable difference 

 exists between the specimens of Doris bilamellata inhabiting the 

 two spots. At Egremont they are all of a large size, being from 

 an inch to an inch and a half long, and more or less mottled with 

 a rich dark brown ; but at Monk's Ferry an entirely diflferent 

 variety occurs : here none of them exceed three-fourths of an inch 

 in length, and many are much smaller, while the dark brown 

 mottling gives place to a much lighter colour ; and even this is in 

 some specimens almost entirely absent, and they become of a dull 

 white. So great a persistent difference in the individuals of one 

 species separated by so short a distance is very remarkable, and 

 would almost seem to give some colour to the idea that they are 

 distinct species. Messrs. Alder and Hancock, however, were 

 unable to fix upon any distinguishing character on which they 

 could rely. At Monk's Ferry they swarm over the lower part 

 of the slip, so that passengers landing from the steamers at low 

 water unconsciously trample them and their ribands of spawn 

 under foot. 



Doris pilosa, — A common and widely distributed species, but 

 by no means one of the most abundant of the Mersey Nudi- 

 branchs. It is a pretty little Doris, and one which varies very 

 considerably in appearance, within the limits of species, not only 

 in colour, but in general aspect. Mr. Price informs me that at 

 Monk's Ferry he has found it of a pale lilac, and even white, 

 spawning upon Fucus serratus. A deep purplish-black variety 

 also occurs in the Mersey ; but I have met with only one or two 

 specimens during the last twelve months. When not in motion, 

 it bears a great resemblance to a miniature hedgehog. This 

 species, as well as D. pj^oxima and some Eolids, have a habit of 



