1888.] Mr G. Brook on a Lucifer-like Decapod Larva. 421 
which were collected at a depth of 8 to 10 fathoms in the Sound 
of Mull, 24th August 1887. These were associated with various 
larval stages of PorceUana, Galatliea, and other Decapods. 
Lucifer belongs to an aberrant section of the Macrurous Decapods, 
and, so far as I know, is the only genus in which in the adult the 
eyes and antennm are carried on a long styliform neck. Brooks 
{Phil. Trans. Roy. Soc. Lond., vol. clxxiii.) has given a full account 
of the development of this genus. The embryo is hatched in the 
Nauplius stage, and passes through a Protozooea stage, very similar 
in many respects to the Galyptopis form of the Euphausiidse. It 
never possesses at any time a triangular plate-like expansion of the 
last abdominal somite (embryonic telson), a feature which is char- 
acteristic of the typical Zooea larva of Brachyurous and Macrurous 
Decapods. In Lucifer the biramous form of limbs characteristic of 
adult Schizopoda is found in the Protozooea stage, but the limbs 
become simple before the characteristic form of Lucifer is reached. 
The uropods are developed early, and make their appearance during 
the earlier Protozooea moults. 
Of the specimens here described the smallest measures 6 mm. in 
length. It has the eyes and two pairs of antennae situated on a 
long slender neck, which is relatively more slender than in Lucifer 
larvae, and the eye-stalks are very short. The segments of the pleon 
are also very slender, the middle ones bearing simple hooked pro- 
cesses at the posterior extremities. The last segment is much 
elongated, and consists of a very long slender stalk-like somite with 
a sub-triangular dilated base, which has a median depression 
posteriorly, and is fringed with stout hairs as in the normal Decapod 
Zooea. At this stage the segment shows no trace of uropods. 
The appendages of the cephalothorax (excluding the neck-like 
portion) consist of a pair of hooked mandibles, two pairs of short 
biramous maxillse, one pair of short biramous maxillipeds (?), and 
two pairs of long biramous maxillipeds. hTo pereiopods are developed 
at this stage, though the rudiments of two pairs may be made out 
as indistinct buds. The largest specimen obtained measures 9*6 
mm. in length, and represents the latest stage to which I have 
been able to trace the metamorphosis. The principal changes have 
reference to the formation of the pereiopods and the uropods, which 
I have been enabled to trace through several moults. 
