rOLYPLACOPHORA. 93 



(1). Species with naked girdle he calls Tonicia. 

 (2). Species with scaly girdle are called ie/)ic?ojt)/e?<n<s if the scales 

 are small, Gijmnojilax if they are larger. 



(3). Species with spinose or hairy girdles are classed — 



a. as Acanthochites if tufts are present. 



b. as Chcetopleura if girdle has hairs. 



c. as ^ca?i</iojo/e«ra if girdle has spines. 



The names Schizochiton, Leptochiion, OnithocJdfon, etc. are used in 

 a variety of senses, or with no sense at all ; but in no case, so far as 

 I can learn, for the groups correctly so termed. Rochebrune's types 

 are in the Paris Museum. 



There are also included herein a few species carefully described 

 by well-known authors, but without reference to the internal char- 

 acters. These are mostly quite recognizable specifically, but they 

 require re-examination to ascertain their generic affinities. 



The species are grouped geographically. 



1. Northern Europe and N. Atlantic species. 



Onitochiton [sic] rhygophilum Rochebrune. Shell ovate, car- 

 inated, ochraceous ; anterior valve smooth ; posterior part of the 

 posterior valve and lateral areas of intermediate valves very minutely 

 granulated; central areas lacuuose at the sides. Marginal ligament 

 somewhat wide, pale rufous. Length 17, breadth 10 mill. {Rocliebr. 

 in Bull. Soc. Philom. de Paris, 1883-1884, p. 32). 



Coasts of Norway (Coll. Petit), rare — Paris Museum. 



Chiton rarinota Jeffreys. Vol. XIV, PI. 4, fig. 86. 



Shell oblong-oval, arched, rather thin and glossy : plates broader 

 in the middle than at the sides ; lateral areas indistinct. Sculpture 

 consisting of white tubercles, which are few in number and irre- 

 gularly scattered ; these are round in the middle of the shell, but 

 become more raised and oval at the sides ; under a microscope can 

 be detected numerous and close-set lines or striae, which are arranged 

 lengthwise ; colour whitish ; beaks none, except on the tail-plate, 

 Where they are nearly circular : inside glossy. (Jeffr.) 



Length 2*, breadth H mill. 



North Atlantic. 



C. rarinota Jeffr., Moll, of ' Lightning' and ' Porcupine ' Expe- 

 ditions, in P. Z. S. 1882, p. 668, t. 50, f 1. 



