1870.] Zoology. 143 



cartilaginous rod, which runs from the tip of the tail to a point 

 near the middle of the head, and round this, which is called the 

 " notochord," bones and muscles develop. It is however an essen- 

 tial and most important feature in vertebrates, that by the rising-up 

 and closing-in of the walls of the body above this notochord a tube 

 is formed, which becomes the great cerebro-spinal nerve-organ, 

 whilst below this axial rod the viscera and blood-vessels lie in a 

 second tube, formed by the closing-in of the walls of the body below 

 the notochord. Now it is a very remarkable fact that the nervous 

 system in these young Ascidians is seen to lie over the gelatinous 

 rod which runs along their tails, whilst the heart and viscera lie 

 below it. The mode of formation of the nerve-system as described 

 by Kowalevsky and Kupffer is the same as that seen in Vertebrata, 

 that is, there is a rising-up of the. embryonic walls to enclose a 

 cavity, and though this part of the observations is not quite 

 definite, it certainly appears as a long fusiform vesicle, which 

 stretches its length through the embryonic Ascidian, being con- 

 nected with a much larger vesicle anteriorily. It does not seem 

 improbable to the believers in evolution that these structures in the 

 embryo Ascidian represent some distant connection in development 

 between them and the Vertebrata. More has to be looked for on 

 this matter, and it is a subject for congratulation that the same 

 brilliant observer, M. Kowalevsky, who has drawn attention to 

 these facts as to Ascidians, should in the same year have furnished 

 us with a most valuable account of the development of the lowest 

 vertebrate, viz. Amjphioxus, the history of which was previously 

 unknown. 



The Significance of Cranial Characters in Man. — Professor 

 John Cleland (spoken of by mistake in our report of the British 

 Association Meeting as Professor McClellan) has communicated 

 'to the Eoyal Society a paper in which he gives an account of 

 some careful investigations into the cranial measurements of various 

 races, and criticizes the various methods of craniometry in use — 

 pointing out what facts of growth and relation of parts the ob- 

 served measurements really indicate. He observes that if the 

 terms dolichocephalic and brachycephalic are to retain any scientific 

 value, as applied to skulls, the " cephalic index" (that is, the 

 breadth in terms of the length which is called 100) must not 

 be depended on. Other points of importance, as pointed out by 

 Eetzius, must be attended to. According to Dr. Cleland, the 

 relation of the height to length of a skull is of great importance. 

 There is no foundation whatever for the supposition, which is 

 a wide-spread one, that the lower races of humanity have the 

 forehead less developed than the more civilized nations; neither 

 is it the case that the forehead slopes more backwards on the floor 

 of the anterior part of the brain-case in them than it does in others. 



