ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
729 
plete closure of the small cleft which alone revealed the presence of a 
Lingula. As in all Brachiopods the vitality is very great. 
On each valve there are five muscular insertions — some for the ad- 
ductors and protractors of the dorsal valve, others, more posterior, for 
the rotators and retractors of that valve. With regard to the circulatory 
apparatus the author has not been able to see the contractile ampullae 
described by Morse as situated in the mantle. In each of the canals of 
the mantle the blood is constantly directed along an outgoing and an in- 
going current, and the boundary of each current is so sharp that one is 
tempted to believe that each series is divided into two parts by a longi- 
tudinal septum. All the vascular ramifications end in rounded culs-de- 
sac, at the bottom of which the current makes a half-turn on itself. 
The arrangement of the trunks is such that each of them and of the 
branches of the sinus-system fulfils by itself at one and the same time 
the function of an artery and of a vein. In the body-cavity the circula- 
tion of blood is aided by the lining cilia ; the mesenteries contain lacunae. 
The body-cavity is prolonged into the arms and stalk ; in the former there 
are three canals — a central sinus, the canal of the cirri and a very small 
labial canal. The author, in distinction to most who have written on 
the subject, regards the mantle and not the arms as the chief organ of 
respiration ; and he thinks that the fleshy and muscular structure of the 
latter, and their thick envelope suffice to show this. 
The blood is opaline and of a rosy violet ; it contains a large 
number of corpuscles. These are more or less conical in form, and are 
from 20 to 25 p, in diameter. 
The stalk consists of several distinct layers — an outermost, delicate, 
chitinous cuticle ; a hyaline gelatinous layer, cartilaginous in consistency, 
and showing in section that it is formed of concentric lamellas ; a delicate 
layer of transverse muscular fibres ; and a layer of longitudinal mus- 
cular fibres ; there is a central cavity in which the blood circulates. In 
life, the stalk looks like a crystalline rod with an opaque white axis. 
In all the living specimens the stalk was seen to end in an ampulla, 
which was gorged with blood, but it has a delicate wall ; it secretes the 
hyaline matter which surrounds the stalk. If, as often happens, a stalk 
is broken at its insertion into the mantle, the wound cicatrizes rapidly, 
and a small bud is formed which begins to elongate : it soon secretes a 
hyaline envelope. Dr. Frangois kept specimens for at least six weeks in 
perfect health ; he observed that they moved the valves of the shell in the 
most remarkable manner, now rubbing them on one another as a man 
does when he hears a piece of good news, and now moving them laterally, 
like the jaws of a ruminant. Now and again they contract rapidly, expel 
the water and draw themselves down on their stalk. 
Arthropoda. 
o. Insecta. 
Embryology of Insects.* — Prof. v. Graber describes the develop- 
ment of Meloe scabriusculus Brdt. At a certain stage the ptychoblast 
shows on its inner side a hint of the ento-merosomites, but there is no 
segmentation of the ptychoblast into macrosomites. As regards the 
* Zool. Anzeig., xiv. (1891) pp. 286-9]. 
3 F 
1891. 
