SCIENCE. 



[N. S. Vol. XVII. No. 430. 



poison claws in Chilopoda, inasmuch as 

 this segment is composed of a protosomite 

 and deutosomite, the former being homol- 

 ogous with the microthorax (see Geophil- 

 idffi). Furthermore, a protosomite homo- 

 dynamous with the 'microthorax' is present 

 in the Dermaptera on the mesothoracic and 

 metathoracic, as well as on the abdominal, 

 segments. Consequently there is evidence 

 for considering that not only is the thorax 

 in Hexapoda composed of six somites, but 

 that each typical segment in the Hexapoda 

 and Chilopoda ( Crustacea and Arachnida 1 ) 

 is composed of two coalesced somites. 

 The Vertebrate Stomach: J. S. Kingsley, 



Tufts College. 



It is usually believed, since the liver in 

 Ampliioxus directly follows the gill slit 

 region, that the vertebrate stomach and 

 oesophagus were primitively included in 

 the respiratory region. In the embryos of 

 the vertebrates, however, the anlage of the 

 liver follows as closely the last gill slit as 

 it does in Amphioxus, and the stomach and 

 gullet are developed, not from the pharyn- 

 geal region, but by rapid growth of the 

 short intermediate region. Hence the 

 stomach in the vertebrate is a new forma- 

 tion without its counterpart in the lower 

 ehor dates. 



The Occurrence of Echinoderm Larvce with 

 Transverse Ciliated Bands: Caswell 

 Grave, Johns Hopkins University. (To 

 be published in the Biological Bulletin.) 

 Serial Order of Segments in the Fore-train 

 of Three- and Four-week Human Em- 

 iryos; Comparisons with Lower Forms: 

 Susanna Phelps Gage, Ithaca, N. Y. 

 (With demonstrations from a series of 

 wax models.) 



A three-week human embryo from the 

 collection of Dr. Mall, of Johns Hopkins 

 University, and shown by him and Dr. 

 Bardeen to have two slight anomalies, pre- 

 sents, in the regions of the fore-brain in 



which the eye and olfactory region are well 

 defined, a third peculiarity. The remnant 

 of the neuropore, the original cephalic open- 

 ing of the fore-brain, is unusually conspicu- 

 ous and consists of a thickened union of 

 the epithelium of skin and brain wall. 

 Here arises a furrow extending toward 

 each eye. The conclusion was reached that 

 this point represents approximately the 

 cephalic end of the original neural plate 

 and that as a corollary, by following the 

 original edge of the neural plate, the 

 olfactory region is morphologically caudad 

 of the eye. 



A finely preserved and entirely normal 

 human embryo of four weeks prepared by 

 Dr. Buxton, of the Cornell Medical School, 

 gives a similar model, except that the 

 neuropore does not show a thickening. 

 Many other mammalian brains of this 

 stage give similar results. 



In a series of chick brains the neuropore 

 was traced to the fifth day, when it was 

 shown to become the recessus opticus. 



Summarizing the results of studies in 

 the earlier stages of chick, Amhly stoma 

 and mouse— the earliest total fold or seg- 

 ment of the fore-brain to appear is the 

 hypophyseal at the cephalic tip of the 

 neural plate ; with growth and curving for- 

 ward of the fore-brain, the eye, second in 

 serial order with relation to the edge of the 

 neural plate, appears; as the eye becomes 

 constricted off the olfactory furrow of the 

 brain appears, entirely dorsal, as shown 

 by His and again (with reference to the 

 edge of the neural plate) following the 

 eye in serial order; next comes the 

 diencephal. From the caudal portion of 

 this original olfactory region arise the 

 folds characteristic of the cerebrum, and 

 from the one furrow of the diencephal 

 the three shown by Minot arise. 



Until certain difficult homologies are 

 made in the hypophyseal region of the 



