428 THE OPISTHOBRANCHIATE 



development of the pigment patches on the papillae of the larger 

 Lomanoti really served to render them inconspicuous). Veil absent 

 in the smaller specimens, very small in the largest, but bearing two 

 short tentacular processes on each side ; these processes of the head 

 appear before the veil itself, and existed in all except the smallest 

 specimen, where the corresponding region was almost perfectly semi- 

 circular in outline, and in the specimen next it in size, in which the 

 future oral tentacles were, however, indicated by short and broadly 

 rounded prominences. In one individual, however, there appeared 

 to be only a single velar process on each side, corresponding in 

 position to the inner of the two normally present. Rhinojyhores 

 clavate, laminated ; the laminee six to ten in number, not so closely 

 set as in Alder and Hancock's marmoratus, and ceasing a little 

 below the tip of the tentacle, which is smooth, conical, and not so 

 sharply truncate as in the latter " species." Rhinophores in the larger 

 specimens retractile within calyx-like sheaths, whose edges were pro- 

 duced into four, five, or six somewhat irregular processes, of either 

 simple, papilla-like, digitate, or compressed triangular form ; of these 

 the postero-external papilla was in all cases the largest (see PL 

 XXVIII, figs. 1 and 2, and cf. the descriptions of L. flavidus and 

 Portlandicus) . During life the rhinophores were constantly being 

 retracted and protruded from the calyx-like sheaths, but some in- 

 dividuals kept their rhinophores retracted for hours at a time, while 

 others were never seen to protrude them at all. In these latter cases 

 the only part of the rhinophore visible was the smooth conical apex. 



On account of the similarity in appearance between this condition 

 of the rhinophores and that which Dr. Norman described as being 

 the most striking feature of his L. Hancocki (1. c, 1877, p. 518 ; 

 1890, p. 81), I wrote to him to ask if the rhinophores of his speci- 

 men had been actually dissected out. With his usual courtesy he 

 has informed me that he did not extract the rhinophores for exami- 

 nation, so that I cannot but be convinced that the appearance which 

 these structures presented in his specimen of Lomanutus was due 

 not in reality to the absence of laminas upon them, but to a tem- 

 porary state of retraction within the sheaths. 



Pleuropodiu7n (= " pallial margin," " branchial curtain," " margo 

 dorsalis," " membrana papilligera," '' epipodial ridge ") on each side 

 in the form of an undulating ridge extending from the sheath of the 

 rhinophore (at the part produced into the large postero-external 

 rhinophoral papilla) very nearly to the posterior termination of the 

 foot, where it approaches the corresponding structure of the other 

 side. The ridge is produced into irregular, flat, triangular papillae, 

 of which four are larger than the rest, and mark the centres of the 

 inward undulations. The ridge in reality consists, as was pointed 



