MOLLUSCA OF PLYMOUTH. 429 



out in my former paper, of a series of four arcuate lobes having 

 their concavities external (cf. Hancockia) , and this statement is borne 

 out by the development. In the smallest specimen (5 inch long) 

 the pleuropodiura is represented only by a series of three small, 

 broadly triangular processes on each side, the smallest posterior, re- 

 calling the condition of this fold in Scyllsea, Glaucus, and Lohiger ;^ 

 the connecting ridge appears later, as in the case of the veil. In 

 slightly larger individuals (y^g- inch) an additional smaller process 

 has appeared on each side of the first three (see PL XXVIII, fig. 1), 

 and another triangular papilla has arisen posteriorly. The posterior 

 papillae are more separated, since the continuous ridge is formed 

 first in front. The papillae of the pleuropodia and rhinophoral 

 sheaths of the two largest specimens were pigmented exactly as in 

 Alder and Hancock's L. Jlavidus ; and on account of their flexibility 

 and contractility there is not in my own mind the least doubt as to 

 the specific identity of these specimens and the so-called "Jlavidus," 

 which was also obtained upon Antennularia. Foot normal in the larger 

 specimens, although the transverse groove was not observed ; in the 

 two smallest individuals the anterior angles of the foot were not 

 produced into recurved processes, but simply rounded. 



It remains to add that the eye-spot is round and black, and 

 situated under the transparent integument beneath the large postero- 

 lateral tubercle of the rhinophoral sheath on the outside (PI. XXVIII, 

 fig. 1) ; and that in the smallest individual the sheath of the rhino- 

 phore consisted merely of a thickening of the skin around its base, 

 whose only tubercle was this postero-lateral one. This tubercle was 

 in direct continuity with the primary papillae of the pleuropodial 

 series — another detail in the resemblance of the young Lomanotus to 

 Scyllsea? This continuity persists throughout life, and can be seen 

 in fig. 1 of my plate (cf. also Bergh, 1. c. supra, 1882, p. 67). 



Alder and Hancock's otherwise beautiful figures of L. marmoratus 

 are seriously wrong in representing a continuity between the pleuro- 

 podium and the oral veil. There is a figure of a preserved L. genei 

 in Mrs. Gray's Figures of Molluscous Animals, 1874 {Gastropoda, 

 pi. ccxxi, fig. 2), which, though not so artistic, is much more correct 

 in this respect. The continuity between the rhinophoral sheath 

 and pleuropodium exists also in Tritonia and Dendronotvs / it is 



1 The pleuropodial fins of Lohiger are, according to M. Vayssiere, folded over tlie back 

 of the animal when at rest, as in Aplysia, Haminea, &c. It is of interest to notice that 

 this habit is still persistent in Lomanotus (see Thompson, 1. c., p. 50 ; and previous Report, 

 1. c, p. 187). 



' Cf. Alder and Hancock on Scyllcea (Monograph): "The orifice [of the rhinophoral 

 sheath] inclines forwiirds, and there is a thin, arched, crest-like appendage behind it." 



3 Cf. Bergh (1. c, p. 5), Bei den Dendronotiden, Bornelliden, vnd Scyllceidenverschmelzen 

 die vordersten JPapillen mit dem Stiele der Rhinophorien. 



