642 SIR c. ELIOT ON NUDiBRANCHS [June 19, 



identical, for, though the variations may be within specific limits, 

 it is equally possible that two dissimilar forms, both varying, may 

 roughly coincide. For the determination of species the most 

 important internal characters are the radula and labial armature, 

 the other organs not varying much in the genus. Good external 

 characters are often furnished by the greater or less development 

 of the dorsal margin, which in several species bears small knobs 

 underneath. In a few species the back bears tubercles or even 

 papillae {Chr. papulosa B., Ghr. ? roseopicta Verrill). The precise 

 number of branchiae is not a character of importance, but the 

 species seem divisible into those where the plumes are few (3-7), 

 moderately numerous (8-12), and many (12-20 or more). In 

 some species the plumes have a strong tendency to develop 

 accessory branches and become bipinnate. 



Ohromodoris (?)amabilis (Kelaart). (Plate XLII. fig. 1.) 

 (Kelaart, 1. c. I. pp. 294-5.) 



This form is perhaps a Ghromodoris, though the bipinnate 

 branchife create some doubt. It may even be Chr. porcata (Bergh 

 in Semper's Reisen, xvi. 2, pp. 831-3), which is white or yellowish 

 with purple spots on the back, yellow rhinophores, white foot and 

 branchise. The gills are 8 and two of them subdivided. It is 

 recorded from Mauritius. 



Ghromodoris fidelis (Kelaart). (Plate XLII. fig. 2.) 



(Kelaart, 1. c. I. p. 295. Bergh, System, p. 1106. 

 Cf. Bergh, Chr. Jlammulata & Ghr. lacfea in Siboga-Expeditie : 

 Opisthobranchia, pp. 151 & 159-160.) 

 This form, which is said to be common at Trincomalee, will 

 probably be recognised by its striking coloration. 



It is possibly identical with Ghr. Jlammulata B., which has 

 black gills and rhinophores, and is said to be red with a broad 

 irregular white patch down the centre of the back. This is merely 

 another way of regarding a pattern which Kelaart describes as a 

 white surface, " the edge lined with red and irregular tooth-like 

 transverse internal prolongations of the same colour." In other 

 details, such as shape, number of branchiae, and the anterior 

 expansion of the foot, the two forms agree. 



Ghr. lactea B. appears to be a closely allied form. It is pure 

 white with black branchiae and rhinophores, and difi'ers chiefly in 

 not having the red border. The radula is much the same as that 

 of Ghr. Jlammulata, but there are some differences in the labial 

 armature. 



Ghromodoris preciosa (Kelaart). (Plate XLII. fig. 3.) 

 (Kelaart, 1. c. II. p. 295. Bergh, System, p. 1106.) 



This form appears to belong to the group of Chromodorids 

 which are somewhat flat and have an ample mantle overhanging 

 the foot all round. 



