332 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
The extraordinary compression of the shell of L. squamosum is now 
intelligible ; it lies flat on the floor of the passage and is not injured 
or affected by the Gebia as it scuttles in and out. 
Entovalva mirabilis.* — Under this name Dr. A. Voeltzkow describes 
a parasitic Lamellibranch found in the intestine of a Synapta. When 
removed from its host the creature moves about actively by means of its 
large foot, on which there is a small sucker ; the shell is small, and the 
whole length is from two to three millimetres. 
When the animal is extended, about one-third of the body is covered 
by the shell, and when it is irritated the whole of it cannot be drawn 
into this shell. The mantle incloses the shell-valves completely, is 
fused along the middle line in its lower part, and leaves only a small 
slit for the passage of the foot. At one end it is continued into a bell- 
shaped enlargement ; this last has strong walls, is hollow interiorly and 
is only traversed by a few muscular fibres ; like the foot, it is in constant 
movement. The author gives a few anatomical details as to various 
organs ; the mollusc is hermaphrodite, and he has been able to observe 
some of the stages of development. No indications are given as to the 
systematic position of this endoparasite. 
In a postscript there are a few notes on a Gastropod also found 
parasitic in the same species of Synapta ; it would appear to be different 
from the parasitic species of Entima discovered by Semper. 
Molluscoida. 
a. Tunicata. 
Blastogenesis of Astellium spongiforme.| — M. A. Pizon finds that 
the newly hatched larva possesses only two ascidiozooids, and not three 
as Giard described. The larva consists of the primitive oozoid with its 
sensory vesicle, a primary blastozooid, and a brown mass which Giard 
regarded as the intestine of a second blastozooid. But there is no trace 
of a second branchial sac ; the brown mass diminishes and disappears 
within 24 hours after hatching ; even after four days there are still only 
two ascidiozooids. This agrees with what Macdonald described in the 
closely related Diplosoma Eayneri , and with Lahille’s description of 
D. KoeJileri. The ectodermic tubes in the mantle of each ascidiozooid are 
not transformed into new individuals ; the five or six blastozooids which 
Giard described on larvse which had been fixed for seven or eight hours 
do not exist. A short diverticulum from the peribranchial membrane 
of the first blastozooid and a slight thickening of the peritoneal membrane 
were recognized as the two rudiments of the second blastozooid of the 
young colony. 
Budding of Larva of Astellium spongiforme and Pcecilogony in 
Compound Ascidians.J — M. A. Giard, referring to the work of M. Pizon 
on A. spongiforme , points out that he has failed to observe that in the 
Synascidire the development and number of blastozoites produced by 
one egg very often largely depends on etiological conditions. M. Giard 
has himself already insisted on this, and Lahille has given a striking 
* Zool. Jahrb. (Abth. f. Systematik, &c.), v. (1891) pp. 619-28 (1 pi.), 
t Comptes Rendus, cxii. (1891) pp. 166-8. X T. c., pp. 301-4. 
