NOTES ON SOME BRITISH NUDIBRANCHS. 349 



given a somewhat detailed description of L. cisigii, from which it 

 appears that its most remarkable characters are : (1) that the hepatic 

 diverticula do not extend into the marginal papilhc; and (2) that the 

 two margins unite at the end of the Ixxly and form " una larga pinna 

 che e r organo principale del nuoto." But a similar organ is found in 

 the specimen described below, and is figured in some unpublished draw- 

 ings of L. iwrtlandicus made by Hancock, and preserved in the New- 

 castle Museum. Alder and Hancock, as well as Bergh, found the 

 hepatic diverticula in the papilla', but 1 could not demonstrate their 

 existence with certainty in the specimen which I examined. It is pos- 

 sible that dilferent specimens may vary in this respect, as do Dendro- 

 notus and Bornella exccpta. Trinchese also states that in the young 

 L. eisigii, " Ogni papilla conteneva un lobo epatico bene sviluppato." 



The small species are L. marmoratus and L. Jlavidus, both British. 

 With regard to these the main question is, have they assumed their 

 adult and final form, or are they immature ? Trinchese states that the 

 young of L. eisigii differs markedly from the adult; and if we recognize 

 the possibility of modifications occurring during growth, it may be said 

 that the two small species present no characters either externally or in 

 the buccal parts which are incompatible with the idea that they are the 

 young of L. genet. On the other hand, if they are mature (on which 

 point the evidence is inconclusive), the differences in size and colour are, 

 no doubt, sufficient specific characters. A further question is whether 

 L. marmoratus and L. jlavidus are distinct forms. If they are adults, 

 they must certaiidy be regarded as separate species. But if they are 

 immature, then considering that L. jlavidus is smaller than L. mar- 

 moratus, and that Trinchese states that the young L. eisigii is seolidi- 

 form, it is probable that L. jlavidus is the youngest stage of the same 

 species. Alder and Hancock note the ;colidiform characters of the 

 type specimen. 



As mentioned below. Alder and Hancock's published plates of 

 L. marmoraius are wrong in representing the dorsal margin as con- 

 tinuous with the oral veil, and the error does not occur in an earlier 

 drawing preserved at Newcastle. 



I recognize provisionally three species : — 



1. L. genei, Verany. 



= L. portlandicus, Thomps. 

 L. hancocki, Norman. 

 L. eisigii, Trinchese. 



2. L. marmoratus, A. & H. 

 r). L. jlavidus, A. & H. 



It is, however, highly probable t,hat both of these latter will prove to 

 be young forms of the first. 



