SO MR. W. K. BROOKS ON LUCIFER: 



The hitst Protozoea stage (Erich tliina). 



The change from the last stage to the next one in the series was actually observed 

 in several specimens, and more than fifty larvae passed through it in the laboratory. 



After the moult the larva, which is shown from the ventral surface in Plate 4, 

 fig. 42, and in outline in fig. 42a, has the characteristics of DANA'S genus Erichthina. 



Its length, from the tip of the rostrum to the end of the telson, has increased 

 to about T^Q- inch, and most of the increase is in the hind body. The carapace also 

 is somewhat elongated (it was a little flattened by pressure in the specimen which 

 was drawn), and the outline of the antei'ior edge is no longer regularly curved. 

 At the base of the rostrum there is a slight eminence where the integument is pushed 

 out a little by the optic ganglion, and at the outer angle there is a much larger 

 eminence which is the rudimentary cornea of the compound eye. The eye itself is 

 now represented by a large conspicuous pigment-spot (fig. 42a, E). 



The appendages have undergone extremely little change, and they are, as before, as 

 follows : the first antennas (A), the second antennas (An), the mandibles (M), the two 

 pairs of maxillas (Mx. I and MX. 2), and two pairs of maxillipeds (Mp. 1 and Mp. 2). 

 The second antennas are still the chief organs of locomotion. 



The hind body is much longer than it was at the stage before, and it is now some- 

 what longer than the carapace. It now consists of nine free segments and an unseg- 

 mented portion (A 5, 6). The first of the free segments (fig. 42, Mp. 3) is much 

 narrower than any of the others, and its outer edges are marked by enlargements 

 which appear to be the rudimentary appendages, the third pair of maxillipeds. None 

 of the segments which follow it show a trace of the appendages, and the thoracic 

 and abdominal ganglia are not yet visible. 



The four segments which follow next after the one with the bud-like processes have 

 rounded posterior edges, while the posterior edges of the next four are pointed. The 

 later history seems to show clearly that those with rounded edges are the first, second, 

 third, and fourth thoracic somites, and that the following ones are the first, second, 

 third, and fourth abdominal somites. It will be seen, then, by a comparison of this 

 with the earlier and later stages, that the somites of the body are all developed in 

 regular order, from in front backwards, but that the first abdominal somite follows 

 immediately after the fourth thoracic, while the fifth thoracic is never developed. At 

 this stage the long unsegmented region (A 5, 6), represents the fifth and sixth abdominal 

 segments and the telson. The two anal pigment-spots are larger than they were 

 during the stage before, and from this time to maturity their colour is a dirty reddish- 

 brown instead of black. 



The "Zoea" stage (Elaphocaris stage of Sergestes.) 



After the next moult, which was observed in a great number of specimens, the 

 larva passes into a stage which is directly comparable, so far as the appendages are 



