Vol. IX] BERRY— NOTES ON WEST AMERICAN CHITONS 17 



had previously outlined in MS. and convinced me that the 

 species was properly regarded as distinct. It is not closely 

 similar to any of our other West American types except 

 only the peculiar little M. sinuata of Carpenter. With this, 

 in dried specimens at least, one finds a degree of careful 

 discrimination necessary, although the present species is dis- 

 tinguished by the following important and, in the scanty 

 material I have had available, apparently constant characters : 



1.) Considerably larger si.^e (x about 1^4). 



2.) Much less high-arched outline. 



3.) Distinctly arcuate side slopes. 



4.) Bright reddish coloration. 



5.) Distinctly raised lateral areas. 



6.) Heavier and moi'e coarsely pustulose diagonal rib. 



7.) Heavier dentation of the sutures, which is strong and 

 distinct in egrctta. 



8.) Fewer and coarser longitudinal ribs of central areas 

 in shells of the same size. 



9.) Strong pitting and appearance of an incipient sec- 

 ondary riblet in front of the diagonal rib. 



Unfortunately none of the Forrester Island simiata were 

 preserved in alcohol, so a direct comparison of the girdle 

 characters as they exist in adequately preserved material 

 cannot be made, though even the dried shells indicate that 

 here also are interesting differences. A single alcoholic 

 specimen of egrctta [284] has furnished the basis for the 

 description of the girdle g-iven in the foregoing diagnosis. 

 A curious circumstance in both this and the dried specimens 

 is that the setae frequently carry one or more encrusting 

 foraminifera. 



The specific name egrctta is chosen because of the resem- 

 blance of the sutural setae to small egret plumes. 



Literature Cited. 

 Berry, S. S. 



:17. Notes on West American Chitons — I. < Proceed- 

 ings California Academy Sciences, (4), v. 7, pp. 229-248, 

 text figs. 1-4, September, 1917. 



