162 



specimen was found between the 16*^ and 17th gill, the genital 

 opening between the I8th and lO^^i gill. As to the position of 

 these openings and the presence of the neural »Schleirakrausen" 

 the same relations occur as in Chiton {Radsia) chierchiae. The 

 number of gills o( goodalli is 60 on the left and 62 on the right; 

 according to Plate these number are 57 and 59. 



As to the neural »Schleimkrausen", Plate writes: »Die Schleim- 

 krausen fehlen sehr vielen Chitonen, wahrscheinlich sogar den 

 meisten, vollstandig, und zwar geht dieser Mangel fast immer Hand 

 im Hand rait einer höhern Differenzirungsstufe anderer Organe" 

 (49, Bd. 2, Heft 2, Pag. 419). As we see this is not the case, for 

 Chiton {Radsia) goodalli Brod. and chierchiae, no doubt, are highly 

 specialised forms. 



The radula of Chiton (Radsia) goodalli Brod. has hitherto been 

 unkuown. I isolated the teeth and have made an illustration 

 (Fig. 31). The middle teeth (M) is broad and blunt; the »Zwi- 

 schenzahn" (Thiele) is seen from above and from the right and 

 has a very peculiar form. The priucipal tooth (H) is broad-based 

 and has a short blunt cusp and a little secondary tooth implanted 

 on the broad base. The side-tooth is flat (S). — The radula of 

 chierchiae has a great resemblance to that of goodalli. The middle- 

 tooth however is broad ; the cusp of the principal tooth is smaller 

 and the marginal plates are broader and stronger (Fig. 32). 



As is seen, there exist a great resemblance to Chiton (Radsia) 

 goodalli Brod. This form however has a smooth surface without 

 any sculpture and the girdle-scales are of a regular hexagonal size 

 and curved, with broad base (Fig. 20) ; they become gradually 

 larger and larger towards the margin of the mantle. I think we 

 have to do with a new species, which, as far is known, is with 

 Acanthopleura spinigera Sow. and echinata Barnes the largest of 

 all the Chitons. 



A key to the specimens belonging to Radsia (H. A. Pilsbry, 

 Man. of Conchol. Vol. 14, Pag. 190) might be: 

 a. Scales of the girdle regular. 



b. Surface smooth goodalli Brod. 



