ELIOT: NUDIBRANCniATA PROM CAPE VERB ISLANDS. 133 



does seem to be clear is, that in the Atlantic there is for Nudibranchs 

 (and probably for many other groups) a faunistic district which 

 extends from the level of the Mediterranean at least as far south 

 as 15° N., whereas in the Indo- Pacific the equatorial fauna extends 

 as far north as Suez and Karachi. The southward limit of the 

 Atlantic sub-tropical fauna is unknown. To the north it gradually 

 ] lasses into the northern fauna, the boundary being somewhere about 

 the British Isles. A good many species are common to both faunas, 

 but the north is characterized by such Dorids as Acanthoduris, Lamelli- 

 doris, Adalaria, etc., and by an abundance of such Solids as JEoUdia^ 

 Galvhia, Corijphella, and Cratena. It is perhaps a mere matter of 

 cliance that the last genus is not recorded from the Mediterranean, 

 but clearly these forms are more abundant towards the north. 

 (runieolis, Chlamylla, and Doridimculus appear to be exclusively 

 northern. 



It is noticeable that several of the forms from the Cape Verd 

 Islands, here described as new, are closely allied to known species 

 (e.g. Staurodoris atypica, Geitodoris reticulata), and many of those 

 referred to known species present well-marked variations (e.g. Tritonia 

 moesta, Doto cinerea, and ISjnirilla neapoiitana). Taken together, these 

 facts suggest that forms found in the Mediterranean and the parts of 

 the Atlantic in about the same latitude become dijierentiated further 

 south. 



As isolated facts of interest may be noticed the habit ascribed to 

 Boriopsilla (? aredata) of sunning itself in tide-pools ; the absence of 

 a penial armature in the young Doridopsis gra7idlflora, suggesting that 

 this feature is developed with age ; and the development of the teeth, 

 as shown in the young Cadlina Clara. 



Tritonia mcesta, Hergh, var. pallescens, n.var. PI. XIV, Fig. 1. 



Tritonia moesta, Bergh : Semper's Eeisen im Arch. Philip., pt. xv, 

 pp 734-736 (1884); Vayssiere, Ann. Mus. Marseille, vol. vi, 

 pp. 100-1 (1901). 

 Mr. Crossland's notes on the living animal are as follows: — 

 " Small and opaque white, with pink organs dimly showing through. 

 Between the bases of the rhinophores some have a broad crescent of 

 dark crimson lake. 



" Of the usual high square-cut shape, but the back slopes gently 

 down to the tail : this is long and tapering, colourless and transparent. 

 The long rhinophore-cups have a light brown tinge. A few specks of 

 dark red occur on the back in some specimens, but several are merely 

 white all over. Velum with 2 long anterior processes, and 2 shorter 

 lateral. Rhinophores long, with a central pillar surrounded by 

 a cluster of delicate tentacle-like processes. Gills, 3 pairs. The first 

 pair largest, with 2 main branches : the rest have simple branches 

 with short papilla like side branchlets. The foot adheres very strongly, 

 and is damaged in several specimens. It is quite colourless and 

 transparent. In some specimens the expanded lateral margin of the 

 foot is seen when the animal is crawling, but sometimes not at all. 

 The anterior processes of the velum may be carried vertically at times. 



