CALYMENE. 



53 



ward. It seems not improbable, from their position and similarity, that these two are the 

 endopodites of the first two appendages on one side of the hypostoma. Specimen 6 shows 

 rather inadequately the endopodites of the second and third cephalic appendages. I have 

 not found other slices showing endopodites of the cephalon. Walcott, in both his restora- 

 tions, has shown enlarged, paddle-shaped dactylopodites on the distal ends of the fourth 

 cephalic endopodites. The evidence for this rests principally on three slices, No. 38 (pi. 

 26, figs. 9, 10), 53 (pi. 26, fig. 12), and 43 (pi. 26, fig. 13). Of these, No. 43 may be dis- 

 missed at once as too poorly preserved to be interpreted. No. 53 does show a section of 

 an appendage which seems to have an unusually wide dactylopodite, but this slice presents 

 no evidence at all as to the appendage to which the dactylopodite appertains, nor can one 

 even be sure that there has not been a secondary enlargement. Specimen 43 shows this 



Fig. 13. Slice through Caylmene 

 scnaria in the plane of the hypostoma, 

 showing the very slender coxopodites 

 beside that organ, the spines on the 

 inner end of one of the maxillulae, 

 and the anterior position of the at- 

 tachment of all these appendages. 

 From a photographic enlargement. 

 Specimen 50. X 4- 



Fig. 15. Transverse section 

 of Calymene, showing method 

 of articulation with the ap- 

 pendifer. The shell is in solid 

 black, the filling of the append- 

 age and appendifer stippled. 

 Traced from a photographic 

 enlargement of the slice. 

 Specimen 63. X 7. 



Fig. 14. Slice 

 through the hypo- 

 stoma and tho- 

 rax of Calymene 

 senaria Conrad, 

 showing the small 

 size of the coxop- 

 odites nearest the 

 hypostoma. Shell 

 in black, append- 

 ages and filling of 

 abdominal cavity 

 dotted. From a 

 photographic en- 

 largement. Speci- 

 men 40. X 3.8. 



feature much less definitely than is indicated by the published photograph and drawing. 

 The segment in question is strongly curved, with a constriction possibly dividing it into 

 two. If it is in its natural position in this section, it obviously belongs to one of the 

 thoracic segments and not to the cephalon. With evidence of difference so unsatisfactory, 

 I prefer to reconstruct the posterior cephalic endopodites on the same plan as those of the 

 thorax. 



Exopodites. Walcott admits that there is no direct evidence of spiral exopodites in 

 the cephalon of Calymene. No one of the sections cutting through the plane of the hypos- 

 toma shows any trace of appendages which could be interpreted as exopodites. 



Thoracic Appendages. 



The large coxopodites of the anterior thoracic appendages are well shown in many speci- 

 mens cut longitudinally, of which Nos. 23, 50, and 55 may be mentioned, since photographs 

 of them have been published by Walcott (pi. 26, figs. 1-4, 1918). The endobases of all 

 taper toward the proximal ends. Transverse slices show sections of the coxopodites which 



