1844.] 443 



The specimen presented to me by Mr. Forbes is a remarkable ex- 

 ception to the general rule, the parts being perfectly preserved, so 

 far as they are exhibited by the fracture of the matrix. The 

 fish is in its natural position ventre a terre. The dorsal integu- 

 ments being removed, the skeleton is distinctly exposed as seen 

 from above. The outer margins of the pectoral fins, and the 

 caudal vertebrte from the termination of the ventral fins, are defi- 

 cient. The preservation of the claspers proves it to have been a 

 male, and (to judge from the development of these organs) of 

 mature age. It corresponds in size w^ith the unique specimen of 

 Asteroderma from the Solenhofen oolite in the collection of the 

 Society, but has little resemblance in other respects to that genus. 

 The negative facts of the absence of all trace of dermal armature, 

 as also of the caudal ribs described in the " Poissons Fossiles," 

 vvrould sufiiciently distinguish it ; we have, however, the positive 

 evidence of the structure of the vertebral column, which is that of 

 a true ray, without any approach to the squaloid character dis- 

 played in Asteroderma. As compared with the recent genera, 

 the circular form of the head eliminates the Lebanon Ray from all 

 save the Torpedos. From the latter family it is distinguished by 

 the smaller number and greater length of the rays of the pectoral 

 fins, by the smaller size of the ventral fins and the tail, as also 

 by other characters, which will be sufficiently manifested in the 

 sequel. The aspect of this fossil is very singular : it may not 

 inaptly be compared to the figure 8, surrounded by a circular 

 border of long divergent rays. The generic name of Actinobatis 

 at first struck me as conveying a good idea of this peculiarity ; 

 but, finding that Agassiz had already appropriated this title to a 

 fossil ray of which some dermal tubercles have been found at 

 Plaisance, I have substituted the name Cyclobatis, which expresses 

 equally well the most striking character of this singular fossil. 

 The anterior or cephalothoracic cavity is circumscribed by the 

 carpal bones carrying the fin digits, which join the rostral carti- 

 lage at an obtuse inverted angle. The mouth extends nearly 

 from side to side ; the teeth are only seen near the symphysis of 

 the jaw, where they are small and discoid ; the tympanic pedicle, 

 extending from the angle of the jaw to the cranium, is broad and 

 strong. The cartilages of the head are crushed ; but the cranial 

 cavity appears small, as also the orbits. Traces of the branchial 

 apparatus are preserved ; but the number of the arches cannot be 

 decyphered. The cartilages composing the thoracic girdle, which 

 forms the fulcrum for the action of the pectoral fins, are broad and 

 strong. The anterior carpal ossicles are also largely developed, 

 being at least a third broader than in a recent ray of similar size. 

 These dimensions are continued until they abut against the an- 

 terior part of the head. The posterior prolongations of the car- 

 pal apparatus diminish in size as they recede from the thoracic 

 girdle, and terminate at the insertion of the last pectoral digit a 

 little behind the pelvic arch. The pectoral fins are very remark- 

 able, and contribute chiefly to the peculiar characters of this ray. 



