3 889.] Zoology. 639 
to derive this element from the auditory capsule. Parker's later view 
derived the malleus from the articulare, and the incus from the quad- 
rate. Salensky (1880) held that the malleus and incus came from 
Meckel's cartilage; Fraser (1882) derived the malleus from the end of 
the mandibular cartilage, and the incus from the proximal end of the 
hyoid, whilst Albrecht (1883) traced all the ossicles to the hyomandi- 
bular, and held that the quadrate was present as the zygomatic process 
of the squamosal. Gradenigo (1887) agrees with Salensky with regard 
to the malleus and incus, but derives the stapes from the hyomandi- 
bular and periotic cartilage. 
Prof. Gadow agrees with Peters in making the quadrate bone equal 
to the tympanic bone of the mammals, and states that no animal pos- 
sesses both an os tympanicum and a distinct quadrate bone. The 
Salientia have indeed a tympanic ring, which Prof Gadow, on Balfour's 
authority, derives from the metapterygoid region of the quadrate. He 
agrees with Albrecht in deriving the ossicles of the middle ear from 
the hyomandibular element of the second visceral arch. This last 
speaker upon the vexed question of the homologies of the suspensor- 
ium and ear bones therefore supports Albrecht in the main points of 
his thesis, but differs in regarding the tympanic bone rather than the 
zygomatic process as the representative in the Mammalia of the saurop- 
sidan quadrate. 
Prof. Lankester on Amphioxus.— E. R. Lankester contributes 
to the Quarterly Journal of the Microscopical Society {X'pxW 2g, 1889) 
a number of valuable particulars concerning the anatomy of the 
lancelet, with special reference to numerical characters. In the living 
animal the atrial chamber projects between the lateral ridges or meta- 
pleura. Between these metapleura the ventral wall is in the living 
animal plaited into longitudinal folds, six or eight upon each side of the 
middle line ; but when the generative products are full grown these 
folds disappear. A large drawing taken from life shows these folds. 
There are not any canals below these ventral plaitings, as was believed 
by Stieda, Rolph, and others. Branchiostoma lanceolatum, the species 
found at Naples, has on an average 61 myotomes; B. elongatum, from 
Peru, has 79 ; B. bassanum, from Bass's Straits, has 75-76 ; B. belcheri, 
from Borneo, 64-65 ; B. caribbceum, from Rio de Janeiro, 59-60 ; and 
B. cultellum has 52. The full number of myotomes is acquired at a 
very early period of life, even before the epipleural chamber is com- 
plete. The true mouth is the small median aperture concealed by the 
oral hood, which latter is really a preoral portion of the epipleural 
