620 Recent Literature. [ September, 
that they have the most intimate relation with the latter. After 
swimming about as ciliated larve, the shell or ectocyst develops 
and the larva becoming stationary, soon assumes the mature 
Polyzoan condition. 
The description of the metamorphosis and mode of budding 
of the polypite in the different forms is fully detailed and illus- 
trated by beautiful figures. As seen 
in Phalangella flabellans (Cyclo- 
stomes) the larva, after becoming 
fixed to some object, consists of a 
white pyriform mass, closely envel- 
oped by an ectocyst, with numerous 
fat globules between ‘the latter and 
the white mass. The ectocyst swells 
into a discoidal sac, with endocyst, 
ectocyst, and an external anhistic 
zone, while the internal whitish mass 
transforms into the polypide. The 
Hic. 9—Molluscan larva. discoidal sac formed by the endocyst 
constitutes simply the basal disc of the primitive cell. The future 
opening of the cell appears on the upper surface of the cell. The 
budding out of the secondary cells of the polyzoarium is then 
described. It begins by the appearance of a cell placed in front 
and below the primitive cell, and which borders it on each side ; 
its secondary cell then divides into two, each 
of which gives successively origin to three cells, 
and we thus arrive at an Idmonea stage, and 
finally the Phalangella stage is reached, the pro- 
cess being a dichotomous mode of budding quite 
analogous to that which produces the cormus, 
spread out in plates, of Escharina. : 
The development of Membranipora pilosa 1S 
given with much detail. The larva of this spe- 
a ies: cies is provided with a bivalve shell, so that it 
levis, primitive cell was by Semper and Claparède considered as 4 
SOT a ae Lamellibranchiate larva, but was proved to be 
poupide feet a young Polyzoan by Schneider, in 1869. Bar- 
spines; o/, opening rois finds it impossible to compare the shell of 
of the cell. this larva to that of the Lamellibranchiates, and 
considers its metamorphosis as like that of other Chilostomes. 
The work must be considered as the most important general 
treatise on the development of Polyzoa in existence, that of 
Nitsche being less complete, though of a high order of excellence. 
FRAZER'S REPORTS OF PROGRESS IN THE DISTRICT OF LORE 
ADAMS, CUMBERLAND AND FRANKLIN COUNTIES, PENNSYLVANIA. — 
Reports C of the Second Geological Survey of Pennsylvania, and 
* Second a Survey of Pennsylvania. Published by the Board of Com- 
$ = 
missioners. J. B. Pearce, Secretary; J. P. Lesley, State Geologist. 
