126 



THE ANATOMY OF VERTEBRATED ANIMALS. 



which thus seem to fringe a lobe of the integument. Hence 

 the fin is said to be lobate. In the other genera, only two of 

 the basal cartilages are present, and some of the radialia 

 come into contact with the shoulder-girdle between then». 

 In addition, the anterior dermal iin-ray is much larger than the 

 others, and becomes directly connected with the anterior basal 

 cartilage. Thus, in the structure of their fins, as in so many 

 other characters, the Ganoidei are intermediate between the 

 Eldismohrancldi and the Teleostei. 



In certain Ganoids, as Lepidosteus, jiccipenser, and many 

 fossil genera, the anterior margins of the anterior fin-rays of 

 the dorsal fins bear a single or a double series of small scales, 

 or spines, called fulcra. 



In Accipenser and Polypterus, 

 spiracula, or openings which com- 

 municate with the mouth, lie on the 

 top of the head, in front of the sus- 

 pensorium, as in many Elasmo- 

 branchs. 



Lepidosteus, Accipensa; and Sea- 

 inrhynchus, have branchiae attached 

 to the hyoidean arch, as in the JElus- 

 mobranchii. They are now called 

 opercular gills. 



In Folypterus the air-bladder is 

 double and sacculated, and the pneu- 

 matic duct opens upon the ventral 

 aspect of the cesophagus. The air- 

 bladder thus becomes exceedingly 

 ''■like a lung; but its vessels are in 

 communication with those of the ad- 

 jacent parts of the body — not with 

 the heart, as in a true lung. 



In Lepidosteus, the ducts of the 



-The female reproductive male and female reproductive organs 

 a of A^ia ?«'.'"^--^^'..«5 are continuous with those bodies, 



Fio. .J3.- 

 organa i 

 tbe open ends of the „ 



ducts; hi oviducts; c, d the and each duct opens into the dilated 



nght and left divisions of tlie , ^ .^^ .^ t i i ^ 



lu-inarj- bladder; e, e, the open- Ureter OI its SIQC. in the other Ga- 



tS-:',XZXToX't. '^oids the proximal ends of the geni- 

 dominal pores; A, the urogenital tal ducts, in both sexes. Open widely 

 "''" *■ into the abdominal cavity. In Fo- 



lypterus the united ureters open into 

 the cavity of the confluent oviducts, while, in the other Ga- 

 noids, the oviducts open into the dilated ureters. (Fig. 42.) 



