452 THE VOYAGE OF H.M.S. CHALLENGER. 



" A. The youngest Zoea stage without eyes in the development of Leucifer reynaudii. 

 Taken north of New Guinea, off Mariannes, March 1875." 



" Specimens in this stage were also taken north of Japan." 



The second stage differs from the first in having increased from T %%^ (0 - 5 mm.) to 

 Tamr (°' 6 7 mm -) 0I " an mcn > measured from the apex of the rostrum to the base of the 

 hairs on the telson. The appendages are similar to those of the first Zoea, but the 

 carapace is elongated, and a pigment-spot represents the future compound eye which is 

 now appearing. 



The Zoea previous to maturity loses the caudal spines by shedding the skin. 



The third stage Professor Brooks has observed in several specimens, more than fifty 

 having passed through it in the laboratory. The form now corresponds in character 

 with our figure on PI. LXXIX. fig. 1, which is 1 mm. in length, and was taken in 

 September 1875, in lat. 2° 34' N. 



Claus in his Crustaceen System (Taf. ii. fig. 1) has also figured this stage as an 

 Erichthina from a specimen that was taken in the Gulf of Messina, and which he says 

 corresponds with the "larva of Leucifer by Willemoes Suhm," but which differs from Suhm's 

 specimen as well as from that figured in this Eeport, on PI. LXXIX. , which was stained and 

 mounted in Canada balsam by Willemoes Suhm, and is probably that from which he made 

 his drawing, in having the lateral extremities of the carapace rounded as in the young 

 of Penseus, instead of being produced to points, as in Suhm's drawings and our figure. 



The description agrees with the figure given by Professor Brooks, 1 except in such 

 points as may be attributed to the treatment our preserved specimen received in mount- 

 ing, or in such details as will be pointed out. 



The ocellus is present in our specimen in the form of a circular transparent lens. 



The eye is represented by a pigment-spot, which Professor Brooks figures as 

 being on the outer side of the second pair of antennas, and posterior to the cerebral 

 ganglion, whereas in our specimen it is on the inner side of the antennas and in contact 

 with the cerebral ganglion, and is much larger and more conspicuous than in Professor 

 Brooks' figures. 



The first pair of antennas consists of a long cylindrical basal joint and a slender 

 terminal one, which ends in two rather long sensory cilia. The second pair is made up 

 of a short, stout, semi-articulate peduncle that supports two branches, one of which, the 

 scaphocerite, is single-jointed and the other Particulate, each being tipped with several 

 long hairs. The scaphocerite in Brooks' and Suhm's figures is multiarticulate. These 

 are the chief organs of locomotion at this period. 



The mandibles cannot be easily determined in our sole specimen, but Professor Brooks 

 describes them as being " cutting blades which are visible in a dorsal view." 



" During the first Protozoea stage it (the mandible), has only one denticle, which is 



1 Lot. cit., pi. iv. fig. 42. 



