ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 37 



Notopterus chitala, a teleost of the Ganges. The glutinous eggs are 

 usually laid on solid bodies, such as stones ; the male emits milt over 

 them ; they are jealously guarded ; seven stages of development are 

 described. 3. The egg-case of ChlloscylUum griseum is described. It 

 has attached to one of the longer sides a very long (134 mm.) and 

 thick mooring cord of a silky (?) material, which would be useful in 

 anchoring the egg-case to any object on the floor of the sea. 4. Intra- 

 uterine embryos are described in a number of Indian Elasmobranchs. 

 In the earlier embryonic stages of the placental forms there is no placenta, 

 but the yolk-sac functions as such. Later on a placenta develops by a 

 modification of the yolk-sac, and nourishment is obtained directly from 

 the blood of the mother. In some cases additional structures or appen- 

 dicula are developed on the placental cord, and these probably absorb 

 the uterine secretion in which the embryo is floating. In the aplacental 

 forms the yolk-sac persists as such through the greater part of the 

 embryonic life, and the yolk is directly taken into the gut with or 

 without the intermediation of an internal yolk-sac. Possibly the 

 branchial filaments help in absorption, and in earlier stages they absorb 

 uterine secretion. The blood-vessels in the mesoblastic portion of the 

 yolk-sac are also absorptive. In later stages special processes of the 

 maternal uterine wall (trophonemata) enter the embryonic spiracles and 

 pour in secretion. The stomach does not function as such during the 

 embryonic period, but is a mere channel to the absorptive colon. 



J. A. T. 



Muscular Metamerism. — Henri V. Vallois {C.R. Soc. Biol., 1920, 

 83, 111-3). In most fishes and Urodela the myosepta which persist 

 in the adult have undergone foldings which completely modify their 

 insertion. The episomatic portion of each myotome does not correspond 

 to one intervertebral space as in the embryo, but extends over adjacent 

 spaces in front and behind. It is not accurate to say that the primitive 

 metameric structure persists in the adult ; the muscular metamerism 

 does not correspond with the skeletal metamerism. The author discusses 

 the state of affairs in higher vertebrates where there is a general 

 disappearance of the myosepta. J, A. T. 



Neuromeres and Metameres. — H. V. Neal {Journ. Morphol., 1919, 

 31, 293-315, ]7 figs.). However doubtful the interpretation of the 

 so-called neuromeres of vertebrate embryos in other regions of the body, 

 the hind -brain neuromeres or rhombomeres can be. explained neither as 

 primordia of adult organs nor as the passive results of mechanical 

 pressure produced by the bending of the neural tube. A phylogenetic 

 interpretation of them therefore appears to be not impossible. Neuro- 

 merism is not seen in the central nervous system of Amphioxus. It is 

 more conspicuous in the embryos of higher Chordates than in those of 

 lower, and it is more conspicuous in the head than in the trunk. 

 Analogous evidence led to the abandonment of the vertebral theory of 

 the skull. The author suggests that the rhombomeres may have arisen 

 in adaptation to the branchiomeric segmentation ; their neuromuscular 

 relations are hard to reconcile with the assumption of metameric value. 



