*9°5-] 



ANATOMY OF PHAL.4ENOPTILUS, RIDGWAY. 219 



On the dorsal surface (Fig. 8) we find a condition quite differ- 

 ent from that shown on the ventral. All of the bronchial rings 

 are incomplete dorsally. Counting forward from the last tracheal 

 ring, we find between the third and sixth rings a cartilaginous 

 bridge situated in the mid-line of the trachea. It is like the carti- 

 lage of the rings, and is, probably, a fusion of the dorsal ends of 

 the fifth, fourth and part of the third rings with an extension to 

 the sixth. This bridge broadens posteriorly, and at the third ring 

 from the last divides, the branches terminating at the last tracheal 

 ring. Down the center of the pyramidal-shaped area enclosed by 

 this fork passes a yellowish rod which is quite resistant to the needle 

 and is probably bony. It extends beyond the ends of the fork. 

 This pyramidal area is bounded posteriorly by a cartilaginous ridge 

 which bends back in the mid-line and gradually fades out on the 

 side as the bronchial half-rings are reached, forming at this point 

 the upper boundary of the membrana tympaniformis interna ( Tym. 

 in.). Below this is another ridge of like structure which forms 

 the lower boundary of the inner tympaniformis. 



Between the dorsal ends of the third, fourth, and fifth half rings 

 there is a round whitish body covered irregularly with yellowish 

 brown spots. About half way between the ends of the next four 

 half rings there is, in the right tympaniformis, a white club-shaped 

 body (PI. I, Fig. 8, x). The membrane is much thinner around 

 its edges than elsewhere. Strands of a dark pigment substance are 

 seen around the edges and over the inner surface of this object 

 when the bronchus is opened. A similar structure has evidently 

 been lost from the left tympaniformis, judging from the appear- 

 ance of the membrane. All of these bodies are probably bits of 

 cartilage. 



III. Female Urogenital Organs (PI. IV, Fig. n). 



The left ovary ( Ov. ) is situated anterior to the left kidney. The 

 oviduct (Z. ovi) , a very much convoluted tube, terminates anteriorly 

 in an infundibulum {Inf.) facing the left ovary. It lies to the left 

 of the pelvic cavity and opens posteriorly into the left side of the 

 cloaca just behind the ureter. The right ovary is absent, but a 

 very much reduced oviduct (A 5 , ovi. ) is present. The infundibulum 

 is readily made out, and slight convolutions of the duct are to be 

 observed. 



