DORIS BILAMELLATA. 



meeting behind, the rest gradually becoming shorter, so as to leave a wedge-shaped, smooth 

 portion at the back of the tentacle. There are fourteen or sixteen laminae ; the apex is small 

 and not much produced. The margins of the tentacular cavities are plain, without tubercles. 

 Branchial plumes small, simply pinnate, rather variable in number, reaching from twenty to 

 twenty-nine in large individuals, but fewer in smaller specimens. They are placed round 

 the vent, in a transverse elliptical groove, nearly straight in front and open behind, the ends 

 being much curved inwards : the included space is strongly tuberculated. Head with a 

 broad veil, having the margins a good deal waved and extended laterally. Foot rather 

 broad, rounded in front, less broadly rounded and extending a little beyond the cloak 

 behind, when the animal is crawling. It is of a yellowish white colour, the liver appearing 

 through the centre of a purplish hue, but not very large. 



The spicula of the cloak are smallish and rather stout, blunt at the points, and more or 

 less bent in the centre, with usually a small inclined spur or branch at the bending. 

 They are arranged in a stellate form round the tubercles. The spicula of the tubercles are 

 very small. 



The spawn forms a compressed coil of one, or, occasionally two volutions, cemented to 

 the surface of stones and rocks by one of its margins ; spreading at the top, and often a 

 little curved outwards, so as to give it a vase-like outline. That of a large individual 

 measured a quarter of an inch in height, and half an inch in diameter at the top ; usually, 

 however, it is not above half that size. The eggs are small and very numerous, showing a 

 slight indication of a linear arrangement in their early stage of development, which 

 afterwards disappears. We have taken the spawn in February, June, August, and November; 

 but the principal breeding season is apparently in February, when large quantities of the 

 spawn may be seen crowded together, forming patches of no inconsiderable size. In 

 August, too, it has occurred to us in abundance. This species has, therefore, probably two 

 breeding seasons, one in early spring, the other at the end of summer. 



This is one of the most common Dorides on all our rocky coasts. It is occasionally met 

 with in considerable numbers between tide-marks, especially in the spring; but a few 

 individuals may be found in such localities all the year through. It varies exceedingly in 

 size, in which respect two varieties are distinguishable, one nearly twice the size of the 

 other, not, however, without occasional intermediate specimens. This disparity of size has 

 led to the supposition that there might be two species, and they have been described as such, 

 but after a careful examination of both kinds, we have been unable to fix upon any character 

 to distinguish them, unless the increased number and greater development of the branchial 

 plumes might be taken as specific ; but we find this character, contrary to what is usual 

 among the Nudibranchs, so very variable in this species, that we have not thought it safe to 

 rely upon it, especially as the very peculiar arrangement of the plumes is the same in both, 

 as well as the colour and markings of the cloak. 



The Doris affmis of Thompson, a specimen of which, presented by our lamented friend, 

 is now before us, was described from spirits, and the elongated character of the lateral 

 tubercles, which was chiefly relied upon, appears to be owing to the state of preservation of 

 the specimen. The same character is given as distinctive in the Boris Mfortiana of 

 Blainville and Leach, which we take to be likewise a variety of B. bilamellata, judging from 

 specimens in the British Museum, as well as from a living example sent us from the Frith of 



