chap, xxn.] DOUBLE APPENDAGES : ARTHROPODA. 



541 



its point is rather worn. Where the index should be, there is 

 a great eminence, bearing apically a second articulated dactylo- 

 podite D\ complementary to D. Between the two dactylopodites 



Fig. 198. Hyas araneus. I. A normal left chela. II. The left chela of 

 No. 831 from the outside. III. The same from the inside. D, normal dactylo- 

 podite. D', extra dactylopodite. j, normal index, f, a small index toothed on 

 both sides. (In Brit. Mus.) 



at the inner side of the eminence there is a fixed short process, 

 j', which is toothed upon both the edges which it presents to 

 the two dactylopodites. Round the articulation of 1)' are setae 

 like those round the place of articulation of D. Specimen in 

 Brit. Mus., kindly shewn to me by Mr R. I. Pocock. 



832. Cancer pagurus : right chela. 

 Dactylopodite and index each double 

 in the way shewn in Fig. 199. Each is 

 toothed on the side presented to the 

 other half-pincer. Note that there is 

 no proof that one or other of these 

 points is not a pair compounded in 

 Position A or P, but since both seemed 

 equally to diverge from the normal plane 

 of the propodite this is most unlikely. 

 Specimen in Museum of Newcastle- 

 upon-Tyne. 



833. Homarus americanus : right chela 

 shewn in Fig. 200, I. Two dactylo- 

 podites separately articulating. Index 

 bifid at apex and bearing two rows of 

 teeth, one on each edge. Dactylopod- 

 ites did not meet index. Faxon, Harv. 

 Bull, vin. p. 260, PL I. fig. 13. 



834. ? Hyas sp. Right chela. Dactylopodite single and in normal 

 plane. Two separate and similar indices, each toothed as usual, 



Fig. l'J'.l. Ki-ht i-h. hi of 

 Cancer pagurus, No. 832. I>\ 

 D 2 , two partially Beparate 

 dactylopodites. I 1 , 1-, two 

 partially separate indices. (In 

 Newcastle Mus.) 



