ZOOLOGY AND BOTANY, MIOEOSCOPY, ETC. 643 



In AncMma the buds and the stolon appear to be two distinct 

 structures, and call to mind the relations wLich obtain between the 

 mammalian embryo and the walls of its containing uterus. This 

 arrangement would be very difficult to explain but for the discovery 

 by Oulianine that the buds of Doliolum arise at the end of the endo- 

 style, and pass to the stolon, to which they become attached, and on 

 which they develope. 



The individuals of a colony of Anchinia appear to function some- 

 times all as males, and sometimes all as females ; but as yet nothing 

 is known as to the characters of the form developed from fertilized 

 ova ; in other words, the organic generation which produces the 

 stolon and gives rise to the sexual buds is as yet unknown. Like 

 the Salpce, the Anchinice would appear to be very short-lived, 

 inasmuch as they are not provided with any organs adapted for 

 pelagic life. 



Development of Brachiopods.* — Led by numerous requests, M. 

 Lacaze-Duthiers publishes an analysis (by MM. Oehlert and Deniker) 

 of the important essay, written in Kussian, which has been published 

 by Kowalevsky. Observations were made on Argiope neapolitana, 

 Thecidium mediterraneum, Terebratula minor, and Terehratulina caput- 

 serpentis. In all these four types we find that the larvae are formed of 

 a cephalic, a thoracic, and a caudal segment. The second of these is 

 alone devoid of vibratile cilia, and it is the one which gives rise to 

 the fold which produces the mantle, the margin of which is alone 

 ciliated. With the exception of Thecidium, the larvae are very 

 active. 



In the Brachiopoda there are two modes of development — in one 

 (^Argiope, Terebratula) the endoderm is formed by the invagination of 

 the ectoderm, while in Thecidium there is delamination. We find in 

 both types much the same history for the mesoderm and the early 

 stages of embryonic development. The author is inclined to think 

 that in Thecidium the dorsal valve of the shell is alone formed by the 

 mantle, while the ventral valve is largely developed from the wall of 

 the caudal segment ; should this be correct, it would follow that the 

 ventral valve of Thecidium does not correspond morphologically to the 

 similarly named part of the shell in the stalked Brachiopods. 



The larvge of Brachiopods have nothing in common with those of 

 Molluscs, though they offer a great resemblance to what is seen in the 

 Chsetopoda ; like them, they have neither velum, foot, nor shell, while 

 they are segmented. The sole difference would appear that in the 

 Brachiopoda segmentation is very early arrested, while in Worms new 

 segments are continually intercalated. The bundles of setae are simi- 

 larly arranged in the two kinds of larvae, while their absence in 

 Thecidium is to be explained by the feeble development of the ventral 

 surface, which again is due to the absence of a peduncle. The 

 existence of setae during the larval stages of the Brachiopods is looked 

 upon as a fact of capital importance, for they are not found in Molluscs, 

 Echinoderms, or in any other worms save the Chaetopods. Nor is the 



* Arch. Zool. Expe'r. et Gen., i. (1883) pp. 57-76. 



