478 



CYCLOSTOMATA. 



Contrast between Hag and Lamprey. 



Palseospondylus gunni. — Under this title Dr. Traquair 

 has recently described a remarkable fossil form from the 

 Old Red Sandstone of Caithness. He speaks of it as a 

 " strange relic of early vertebrate life." 



It is a dainty little creature, somewhat tadpole-like at 

 first sight, usually under an inch in length. The following 

 characters point strongly to its affinities with Cyclo- 

 stomata :— 



(i) "The skull is apparently formed of calcified cartilage, and 

 devoid of discrete ossifications." An anterior part is comparable to 

 the trabecular and palatal region of a lamprey's skull ; a posterior part 

 is comparable to the parachordal region and auditory capsules. 



(2) "There is a median opening or ring, surrounded with cirri, and 

 presumably nasal, in the front of the head" (»., Fig. 202). 



(3) "There are neither jaws nor limbs." 



(4) "The rays which support the caudal fin expansion, apparently 



