78 MR. W. K. BROOKS ON LUCIFER: 



The second Protozoea stage. 



As my season's work at the sea-shore ended the day the Nauplius shown in fig. 2G 

 turned into the Protozoea shown in fig. 27, I was not able to trace the development 

 of that specimen ; but on September 14th I had captured and drawn a larva in the 

 same stage, and this moulted, while isolated in a watch-glass, into the second 

 Protozoea which is shown from above in Plate 3, fig. 34, and from the right side in 

 Plate 4, fig. 35. 



This larva measures yij-o inch from the tip of the rostrum to the fork of the telson. 

 The appendages are like those of the first Zoea in number and structure, but there is 

 a well-marked difference in the shape of the body. The carapace is somewhat 

 elongated, its anterior edge is less perfectly rounded than before, and a pigment-spot 

 (fig. 34, E) represents the future compound eye. 



The pouches of the stomach (s) are much more conspicuous than before, and the 

 oesophagus (fig. 34, cc) is visible in a dorsal view, between its anterior or cephalic 

 lobes. The four somites of the hind body (Mp. 3, T I , T 2, and T 3) have become short, 

 but there is, as yet, no trace of their appendages. The unsegmented portion of the 

 abdomen (abd) has increased in length, as have also the spines of the telson (T). The 

 two pairs of antennfe have substantially the same form that they had during the 

 Nauplius stage, and they are still the chief locomotor organs. The larva swims by 

 jerks like a Nauplius or a Copepod. 



The appendages at this as well as at the preceding stage are as follows (see Plate 4, 

 fig. 35) : the long uniramous first antennae (A) ; the biramous second antennas (An.); 

 the cutting mandibles (J/); the biramous first and second maxilla 3 (M.r. 1, M.c. 2) ; and 

 two pairs of biramous maxillipeds (Mp. 1, Mp. 2). 



The first antennse consist at both stages (figs. 27, 34, and 35, A) of a long 

 cylindrical basal joint which carries a few short hairs, and a short pointed terminal 

 joint or flagellum, which ends in two long rather thick sensory hairs. 



The second antenna) (figs. 27, 34, and 35, An ; and fig. 36) are the chief locomotor 

 organs, and are made up of a short stout two-jointed basal portion, a longer unjointed 

 exopodite (ex), with four long terminal swimming hairs, and a longer endopodite (en), 

 which is made up of two short proximal rings, and a series of six longer joints, each 

 of which carries one, and the terminal one four, long slender swimming hairs. 



Underneath the rostrum (fig. 35, R) there is a little elevation upon which the ocellus 

 (Oc) is situated. 



The labrum (fig. 35, L) has been carried on to the ventral surface of the body, and 

 its anterior angle has become produced into a short .stout, sharp spine, which is 

 extremely small during the first Protozoea stage. 



As has been stated, the compound eye is represented at the second stage by a 

 pigment-spot (fig. 35, E). 



The mandibles (J/), (figs. 27, 34, 35), have become reduced to cutting blades, which 

 are visible in a dorsal view, and all traces of the Nauplius limb have disappeared. 



