ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
441 
as 10 cm. long, with which, he Las made observations on the circulatory 
and renal organs ; in all, four species havo been studied. 
The structure of the heart is the same in all, but differs in many 
points from the description given by Bela Haller ; each auricle pours its 
blood into the ventricle by two openings, an anterior which is clearly 
identical with that seen by Haller, and by a posterior one which is some 
distance from the hinder end of the ventricle. With regard to the 
supply of vessels from the aorta to the gonad, there is a constant 
difference in the two sexes ; in the male, there are given off from the 
ventral side of the aorta numerous delicate vessels, which pass into 
the lumen of the testis, and are arranged in two rows ; in the female, 
the ovarian vessels are arranged in one row, and are stronger. A good 
many details are given ; the author finds there is no direct connection 
between the aorta and the pedal vessels ; the venous blood does not 
collect in the coelom, and pass thence by a transverse lacuna into the 
branchial artery, but is collected in the deepest part of the body, 
the foot, and passes thence directly by means of the pedal sinus to the 
branchial artery. 
Sedgwick’s account of the structure of the kidney is preferred to 
that of Haller, as he correctly distinguished the efferent duct from the 
renopericardial canal. Both, however, overlooked a considerable part 
of the organ; there are in the foot two delicate canals which run 
parallel to the median blood-sinus ; these the author calls the median 
renal ducts in contrast to the already known lateral ducts ; they give 
off a large number of small, arborescent lateral branches, some of which 
project freely into the coelom. There are also other canals in the foot 
given off from the renal sacs, the presence of which has been altogether 
overlooked. 
The renopericardiac duct varies in length somewhat in the different 
species, and there are also differences in the size of the renal sac. 
5. Lamellibranchiata. 
Sense of Light in Eyeless Bivalves.* — Dr. W. A. Nagel notes that 
many eyeless bivalves have a very keen sense of light. The critical 
experiment implies observing that the animal moves on being suddenly 
shaded or illumined. Animals may be “ skioptic,” or “ photoptic,” or 
“ photoskioptic,” without being “ ikonoptic.” Graber’s wider term 
“ photodermatic ” includes all the reactions due to the influence of light 
on skin sense-organs. 
Nagel’s experiments show that Ostrea edulis , Cardium oblongum , and 
Venus gallina are almost exclusively skioptic ; Cardium tuberculatum , 
C. aculeatum , Venus verrucosa , Cytherea chione, Mactra stultorum vary 
from being skioptic to being also photoskioptic ; PJiolas dactylus, Litho- 
domus dactylus , Mactra helvacea , Tellina complanata are photoskioptic ; 
Tellina nitida , Solen siliqua and S. ensis , Tapes ( Venus ) decussata vary 
from being photoptic to being photoskioptic ; Lima hians , Psammobia ves- 
pertina , and Capsa fragilis are photoptic ; Solecurtus strigillatus , Loripes 
lacteus , and Cardita sulcata are not sensitive to either light or shade, but 
perhaps the slight opening of the shell should be more considered. 
Biol. Centralbl., xiv. (1894) pp. 385-90. 
