Fjebkuabt 9, 1883.] 



SCIENCE. 



23 



size. The tiypoglossus must therefore be considered 

 to have been formed by the fusion of at least three 

 spinal nerves. As is well known, it makes its exit 

 through the occipital bone, which must therefore be 

 regarded as formed by the fusion of several vertebrae. 

 This, again, forces us to the conclusion that the 

 skull is not identically composed in all animals, but 

 that in the mammals portions of the primitive cer- 

 vical region have been added to the head, the por- 

 tions thus added being the hypoglossal region. 



At px-esent, therefore, we must consider the head 

 as made up, in mammals, of three divisions : 1°, the 

 prepituitary or trabecular region, bearing the nose 

 and eyes, and corresponding to the upper face; 2°, 

 the pseudo-vertebral region, which gives off the 

 nerves, namely, trigeminal, facial, glosso-pharyngeal, 

 and vagus, supplying the visceral arches or pharyn- 

 geal clefts. (The vagus, as is well known, is sup- 

 posed to be the product of the fusion of several 

 nerves. ) 3°, the vertebral region, that of the occipi- 

 tal bone and hypoglossal nerve. This is an entirely 

 new start in the interpretation of the morphology of 

 the head. 



The ganglion of the hypoglossus is not permanent. 

 It is always smaller than the spinal ganglia, but for 

 a while it enlarges with the growth of the embryo; 

 it then remains stationary, and becomes finally atro- 

 phied. Dr. Froriep's clear and concise presentation 

 of his subject, and his philosophic grasp of its far- 

 reaching conclusions, as well as his modest tone, 

 deserve high praise. His short article should be 

 familiar to every morphologist. His observations 

 were made principally on sheep embi70s, and by 

 means of longitudinal sections. Embryos of from 8 

 to about 18 mm. long show the development of the 

 hypoglossus. — (Arch. anat. physiol., anat. abtheil. 

 1882, 279) c. s. M. [59 



Origin of the vertebrates. — Mr. C. O. Whitman 

 described a rare form of the blastoderm of the chick, 

 in which the primitive groove extended to the very 

 margin of the blastoderm, terminating here in the 

 marginal notch first observed by Pander. The blas- 

 toderm was eighteen hours old, and nearly one centi- 

 metre in diameter. The extension of the primitive 

 groove to the marginal notch was regarded as a re- 

 appearance of a developmental feature, which is 

 constant in some of the lower vertebrates and their 

 nearest invertebrate allies, but which has ceased to 

 be a normal occurrence in the development of the 

 chick. The blastoderm, interpreted as an atavistic 

 form, was held to be an important confirmation of 

 the theory put forward by His and Eauber, accord- 

 ing to which the vertebrate embryo arises by con- 

 crescence of the two lateral halves of the germ-ring. 

 The objections made to this theory by Balfour were 

 reviewed, with a view to showing that they presented 

 no serious difficulties to the acceptance of the con- 

 crescence theory. Mr. Whitman maintained that 

 Balfour's objections were not broad enough to cover 

 his own theory of the origin of the vertebrates from 

 annelids, — a theory which gave us a right to expect 

 some fundamental agreement in their modes of de- 

 velopment. This agreement, he contended, was seen, 

 first, in the origin of the embryo from a germ-ring, by 

 the coalescence of the two halves along the axial line 

 of the future animal ; and, secondly, in the metameric 

 division, which followed in the wake of the con- 

 crescence. The theory of the annelid origin of the 

 vertebrates was inconsistent with the denial of the 

 concrescence theory, since concrescence of the germ- 

 bands is a well-established fact for both chaetopods 

 and leeches. The theory of differentiation set up by 

 Balfour in opposition to that of concrescence entirely 



ignored the annelids, and offered no explanation of 

 the uniform relations of the embryo to the germ-ring. 



— [Bost. soc. nat. hist; meeting Jan. 3.) [60 



Fish, 

 Use of the BaTw in Pristis. — In jiresentiug the 

 beak of a saw-fish (Pristis) from the Lake of Bay, 

 Philippine Islands, Dr. S. Kneeland suggested a use 

 for this toothed projection, in this specimen thirty- 

 three inches long, which seems more reasonable than 

 the ones usually given; viz., that it is an instrument 

 for more or less horizontal insertion in the mud or 

 saud of shallow waters, which, by a vigorous sweep 

 of the long upper-lobed, shark-like tail, is quickly 

 pulled out backward. The lateral teeth are sharp- 

 edged in front for easy insertion, but concave behind 

 to offer resistance, and more thoroughly stir up the 

 bottom; this action is doubtless accompanied by a 

 series of short horizontal movements of the anterior 

 part of the body. The mouth is small, underneath, 

 with pavement-like teeth, as in the rays, adapted for 

 crushing the mollusks, crustaceans, and hard-cased 

 creatures on which it feeds. He thinks the stories of 

 its attacking in open sea the smaller cetaceans are 

 errors of observation, arising from confounding the 

 saw-fish with the sword-fish (Xiphias); neither its 

 weapon, its mouth, its teeth, its habitat, nor its habits, 

 can be reconciled with the active carnivorous pro- 

 pensities ordinarily ascribed to it. Eay-like, it is a 

 bottom feeder, with crushing and not tearing teeth: 

 the snout is too blunt for piercing, and its lateral teeth 

 would be an impediment rather than an advantage. 



— {Bost. soc. nat. hist.; meeting Jan. 3.) [61 

 Digestion in fishes. — Charles Pachet finds in car- 

 tilaginous fishes of the genera Scylhum and Acan- 

 thias, that the gastric secretion is extremely acid and 

 contains pepsin. This pepsin differs from that of 

 the warm-blooded animal in that it acts as well at 

 20° C. as 40° C, and for its best activity needs a much 

 more acid medium. There is no trypsin in the gas- 

 tric secretion, though this has been found in other 

 fishes. As regards the pancreas, Kichet comes to direct 

 issue with Krukenberg, who states its secretion in 

 these fishes contains trypsin but no amylolytic fer- 

 ment. — {Archiv. de physiol, X. 18S2.) h. n. m. [62 



Fangs of the rattlesnake. — Dr. Leidy exhibited 

 a series of fangs obtained from a rattlesnake fifty- 

 two inches in length. The rapidity with which the 

 functional fangs are reproduced was indicated by the 

 presence, on each side of the jaw, of five fangs in 

 varying degree of development, so placed as to re- 

 place those which are lost. — {Acad. nat. sc. Philad.; 

 meeting Jan. 2.) [63 



Birds. 



An hermaphrodite bird. — The subject of this 

 paper by Mr. Jeffries is a green-tailed towhee from 

 Colorado. On dissection the bird was found to pos- 

 sess a normal ovary and duct on the left side, and 

 a normal testicle and vas deferens on the right side. 

 Owing to the early time of capture, and to insufficient 

 means of preservation, the presence or absence of 

 spermatozoa could not be affirmed. The kidneys 

 of the bird showed slight anomalies. The plumage 

 was that of a female. — {Bull. Nutt. ornith. club, viii. 

 No. 1.) J.A.J. [64 



Peculiar air-sacs. ^ M. Boulart has found a pair 

 of air-sacs which lie on the sides of the neck, and 

 communicate with the nasal cavity, in Leptoptilus 

 crumiiiiferus, Ciconia alba, Mycteria australis, and 

 Sula bassana. In these cases there is no communi- 

 cation with the air-sacs supplied by the lungs. In 



