126 



Palpi elongated, filiform, 10-jointed; three basai joints small; 

 fourth joint very long ; fifth joint shorter than the fourth, vnth a 

 slight hook at the end ; sixth joint about the šame length as the fifth, 

 but without hook at the end ; four lašt joints short, somewhat cun-ed. 



Legs eight, somewhat hirsute, the third leg perhaps shorter than 

 the others. 



Tarsi •with one claw, the under-side furnished with many small 

 spines. 



Hab. South Seas. Capt. Sir Edw. Belcher, R.N. 



This may possibly be the other sex of the preceding. Neither of 

 them have any trace of oviferous legs. 



Additional Observations on Chitones. By j. e. Gray, Esq., 



F.R.S. ETC. 



Since the publication of my former paper I have continued my 

 researches on these animals, and now propose to add four groups to 

 those which I then described : three of these genera were proposed 

 as sections of the genus Chilon in my former paper, but I have since 

 found that they each present peculiar modifications iif Itie structure 

 of the plate of insertion of the valves ; and the other is^ a genus which 

 I had overlooked, though founded on t\vo of the Englisb species of 

 the family. On re-examination I think that the genus Chiton should 

 be confined to the species \vhich have a singl^-notch on the plate 

 of insertion of the centrai valves, and the edge of the plate of inser- 

 tion pectinately lobed, which is the case -vvith the species marked as 

 belonging to the section * and ** p. 66, ežcept Chiton Barnesii and 

 Ch. evanidus. 



1. Radsia. 



Posterior valve entire ; margin covered with regularly -disposed im- 

 bricated smooth scales ; margin of insertion of the centrai valves 

 pectinately divided, and each furnished \vith two notches. 



Radsia Barnesii. Chiton Barnesii, Gray. 



2. Callochiton. 



ITie valves keeled, the hinder valve entire ; the platės of insertion 

 rather short, thick, of the terminai valves divided into many, and of 

 the centrai valves into four bifid lobes. Margin with imbricate 

 scales. 



* Margin with lanceolate, elongate, erect, closely-pressed scales. 



Callochiton IseA-is. Chiton Isevis, Mont., Lotve, Z. Jour. v. t. 5, f. 1 . 

 Ch, discors, Maton 8; Racket. Ch. punctulatus, Maton. Ch. septem- 

 valvis, Mont. Ch. corallinus, Risso. 



** Margin tvith ovate imbricate scales. 

 Callochiton evanidus. Chiton evanidus, Soįv. III. f. 139. 



3. ISCHNOCHITON. 



Valves thin ; posterior valve entire ; the platės of insertion very 

 Ihin, smooth-edged, of the centrai valves each with a single notch ; 

 margin covered with very small imbricate scales. 



