140 Mr. W. K. Parker on the Structure [Dec. 16, 



auditory region the occipital arch and the two auditory capsules are one 

 continuous tract of bone. 



The stapes is perfect, and so is the columella with its two shaft-bones 

 in each stem ; its extrastapedial is like that of Dactylethra. 



The mandible is perfect, the cerato-hyals completely gone, and the 

 branchials are metamorphosed as completely (save that the " thyro-hyals " 

 are not ossified) as in the adults of other Batrachia. 



The frontals and parietals have already coalesced ; in front there are 

 nasals, preorbitals, and septo-maxillaries, a pair of each ; but there is no 

 vomer; there is a pair of styloid palatine bones. 



The premaxillaries and maxillaries lie entirely on the under or palatine 

 surface ; there is no quadrato-jugal. 



In the adult the bones are very coarse, fibrous, and with strong ridges 

 and deep excavations, as in certain osseous fishes. There is no " girdle- 

 bone ; " the quadrate is now well ossified, and so is Meckel's cartilage, 

 the " articulare " having grafted itself upon the rod. 



In neither of these aglossal toads is there a " mento-Meckelian" bone 

 formed at the sj^rnphysis. 



In the adult Pipa the " occipito-otic" masses are stretched far out as 

 large bony arms, on the end of which is the exquisite tympanic apparatus. 

 Both in young and old the superoccipital region is well ossified over as a 

 complete bony arch, and now, in the adult, the occipital condyles look 

 outwards ; the basioccipital region is a narrow synchondrosial tract. 



These are some of the most noteworthy things in Dactylethra and in 

 Pipa. The common toad shows most important differences from the 

 common frog ; but these aglossal types are rich in morphological variation 

 and full of morphological meaning. 



The satisfaction accruing to my own mind from the working out of 

 these three (as well as other) types of the Batrachian skull will act as a 

 strong stimulus to keep me a few years longer at the morphology of that 

 group. 



As the attachment of the mandibular arch to the skull is complex and 

 very important, I venture to add a few remarks upon it. 



On the " Suspensorium " or Pier of the Mandibular Arch in the Amphibia 



The Amphibia agree with three groups of fishes (namely, the " Mar- 

 sipobranchii," the Chimseroids, and the " Dipnoi ") in having their suspen- 

 sorium confluent with the skull. 



The simplest form of such a confluence has been shown in the present 

 paper in the early condition of chondrocranium of the common toad, 

 where the apex or dorsal end of the mandibular arch, during chondri- 

 fication, unites with the outer side of the trabecular arch near its 

 dorsal end. Afterwards, in the same type, this confluence is much 

 more complex. 



