CORRESPONDENCE. 



To the Editor of the American Naturalist: 



Sir: — A little over a year ago Dr. William Fatten 1 claimed to 

 have discovered evidence of "numerous pairs of jointed oarlike 

 appendages " in Tremataspis and related forms, in none of which 

 had similar indications been previously detected. Nor, for that 

 matter, had anyone previously had the temerity to attribute more 

 than two pairs of limbs to any vertebrated creature, living or 

 fossil. Beyond Dr. Patten's assertion that Cephalaspis is pro- 

 vided with "a fringe of jointed and movable appendages (25- 

 30 pairs) along the ventral margin of the trunk," we haw had 

 from him no further enlightenment as to the ambulatory equip- 

 ment of this Ostracophore, but there has recently been heard 

 from Dr. GaskelP an absolute denial of the existence of seg- 

 mental appendages in that genus. 



Now, since it appears that segmented appendages are wanting 

 not only in Cephalaspis, but universally amongst the Heteros- 

 traci and Osteostraci so far as known, the presumption is certainly 

 very strong that they do not occur in Tremataspis, whose close 

 relationship with Cephalaspis none will question. Professor 

 Patten, however, in returning to the matter de novo* combats 

 against this presumption, and affirms his belief in the existence 

 of not only one, but possibly several pairs of jointed appendages 

 in Tremataspis. Naturally he must have strong reasons for 

 inclining him to so heterodox a notion, and what are they, 

 palaeontologists are curious to know ? Has he discovered speci- 

 mens showing one or more pairs of these chimaerical organs 



36. 1902, pp. 379-393- 



