70 REPORT—1852. 
ZOoLoey. 
On a peculiar Annelidan Larva. By Prof. ALtman, MD., MARIA. 
The author described a minute Annelidan larva, which he obtained in abundance 
in a small towing-net in July last off the coast of the county of Cork. It is vermi- 
form, and swam about with great activity, the locomotion being chiefly effected by 
the aid of ciliated discs, which are borne on the fourteen segments which imme- 
diately succeeded the head. Lach disc carries a pencil of very long vibratile cilia; 
and four such discs are carried by each segment. 
The disc-bearing segments are followed by about twenty others much smaller 
and destitute of discs. ‘The terminal segment is encircled by a wreath of very long 
cilia. Dorsal and ventral oars are present on all the segments. The dorsal oars 
carry cirriform branchial appendages densely clothed with minute vibratile cilia. 
The sete are largely developed ; and in each pencil of set carried by the disc- 
bearing segments there are two stronger and longer than the others, denticulated 
and beautifully iridescent. A pencil of very large and beautifully iridescent sete 
is borne by the head. A prominent ridge on the upper surface of the head is set 
with thread-cells. The mouth is situated on the inferior surface of the head. The 
alimentary canal is straight, dilated into a large sacculus in each of the fourteen 
large anterior segments; in the smaller posterior segments the canal presents but 
slight dilatations. 
The little larvee were preserved in a phial of sea-water, and after about a week 
were seen to be transformed into minute Annelides, nearly resembling Nereis. Their 
death shortly afterwards prevented all subsequent observation on their development. 
On the Universality of a Medusoid Structure in ihe Reproductive Gemma 
of the Tubularian and Sertularian Polypes. By Professor ALLMAN, 
M.D., MRA. 
In this communication it was the author’s object to show that the Medusoid 
structure was not confined to the free locomotive gemme of the Tubalarian and 
Sertularian Polypes, but that a similar structure was also possessed by the fixed 
capsules of the Zubularide, and by certain fixed organs found in the ovarian vesicles 
of the Sertularide; that the Tubularian and Sertularian Polypes therefore produced, 
by a process of gemmation, fixed as well as free Meduse, the real office of both being 
apparently the production of ova by a true sexual process. 
In the marine Tubularide, the capsular bodies which contain the ova consist of a 
closed vesicle whose walls are composed of cells, and having a hollow peduncle pro- 
jecting into it from the point of its attachment to the Polype-stem, the cavity of the 
peduncle being in direct communication with the general cavity of the polypary. 
The hollow peduncle here manifestly represents the stomach of a Medusa with the 
mouth permanently closed, and the vesicie only requires to be open anteriorly, to 
complete its resemblance to the bell-shaped disc. ‘The system of gastro-vascular 
canals, which in the ordinary Meduse radiate from the stomach towards the margin 
of the dise where they intercommunicate by means of a circular vessel, are, it is 
true, here wanting, and the absence of this part of the medusan organization may 
at first sight appear to invalidate the view here taken. That the absence of the ra- 
diating canals in the marine Tubularide however affords no real ground for objection, 
is proved by Cordylophora, their freshwater representative. 
In this curious genus, the reproductive capsules, altogether homologous with those 
of Tubularia and its marine allies, present a well-developed system of branched tubes 
communicating with the base of the peduncle and extending forwards in the walls 
of the capsule. These tubes will easily be recognised as the true equivalents of the 
gastro-vascular canals of the Medusz, and at once complete the series of homologies 
between the fixed sacs of the Tubularide and their locomotive medusoid gemme. 
The contents of these sacs are either bodies presenting ail the characters of true 
ova, with the germinal vesicle, and in many instances the germinal spot, and ex- 
hibiting the phenomenon of yelk-cleavage and the subsequent steps in the develop- 
ment of the embryo, or else they present no appearance of ova and are merely com- 
posed of a multitude of minute corpuscles, endowed in some cases with independent 
