1888.] Mr G. Brook on a Lucifer-like Decapod Larva. 423 
The pereiopods, when first formed, are biramous in Lucifer^ and 
only become simple at the close of the ScMzopod series of moults ; 
but, it must be remembered, at a period prior to that at which the 
pereiopods are developed in the species here described. In Lucifer 
a fifth pair of pereiopods is never formed, whilst the fourth pair 
atrophies during larval life. 
In Lucifer the pleopods, present as simple appendages at the end 
of the ScMzopod series of moults, become biramous when the 
Lucifer form is reached. Finally, the three most important differ- 
ences may be summed up as follows : — 
1. Presence of five pairs of pereiopods in the present form, while 
there are in Lucifer only three in the adult and four in the embryo. 
2. Presence of the triangular form of telson in this species, 
characteristic of the normal Decapod Zooea. 
3. The relatively much later period at which the pereiopods and 
uropods are developed in the form now described. 
As this larva, therefore, differs from any with which I am 
acquainted, I propose to give it the name Trachelifer, in reference 
to its elongated neck. At present I am unable to offer any definite 
opinion as to its affinities, but the presence of five pairs of pereiopods 
would appear to show that it is either the larva of some normal 
Decapod which passes through a Lucifer-like stage, or that in the 
adult condition it may represent a new form more closely related to 
Lucifer. I trust, however, that I may be able to follow the 
metamorphosis further next summer. 
6. On Invertebrate Blood removed from the Vessels, and 
entirely surrounded by Oil. By Professor John Berry 
Hay craft and E. W. Carlier, M.B. 
{Abstract.) 
A grant was made by the British Medical Association, on the 
recommendation of the Scientific Grants Committee of the Associa- 
tion, towards the expenses of a research, a part of which appears in 
this communication. 
The authors of this paper read before the Society during the 
