Report on Larval Grabs. 13 



III. ZoEA. — The main difference noticed between the Zoese of holsatus 

 and jmber was in the telson. The prong of the telson of holsatus (fig. 20) 

 had three teeth on its external edge, while that of jnober (fig. 42) had two. 

 The telson of jjuber appears to be rather broader than that of holsatus. 

 The long spines of the telson ai'e in holsatus practically equal ; in puber 

 the middle one of each set of thi-ee is the largest. 



Differences may be observed in the rostral spine in respect to its length, 

 sti-aightness, and curvature. But these are difficult to found upon, as the 

 position in which the Zoea lies, or slight damage, may alter the appearance 

 of the part. It is probable, however, that some distinguishing characters 

 might be made out from the large spines. 



The difference between the antennse of the two species, which is of value 

 in the IV. and V. stages, was not sufficiently marked to be of much value. 



IV. Zoea. — The telson furnished distinguishing characters between 

 the species. As in the preceding stage, the prong in holsatus had three 

 teeth, and in puber two teeth. The telson of puber is of a broader build 

 than that of holsatus. The spines in the angle of fork differ in the two 

 species. In holsatus (fig. 23) they remain veiy small, whereas in 2^uber 

 one pair is much larger than the other, having more of the character of a 

 spine (fig. 48). The relative length of the long spines was as in the pre- 

 ceding stage. 



Differences are to be seen also in the antenna. The serrated branch of 

 this appendage, when compared with the jointed branch, is much longer in 

 holsatus than in puber. 



V. Zoea. — In the telson the same differences hold as in IV. Zoea. The 

 telson of puber (fig. 38) did not, however, appear broader than that of 

 holsatus (fig. 22). 



The new developing branch of the antenna was in holsatus much shorter 

 than the serrated branch ; in puber it was as long as, or longer than, that 

 branch (fig. 34). In holsatus the jointed branch without its terminal spine 

 was about half the length of the serrated branch, while in puber it was 

 two-thirds the size of that branch. 



Mega:lops. — The differences between the Megalopa. of holsatus (fig. 3) 

 and /)it6e?' (fig. 11) are well marked. Fuber has a longer rostrum, and it 

 has a dorsal spine. Thei-e is no dorsal spine in holsatus. The long teeth 

 on the coxopodites of the second, third, and fourth pereiopods had a more 

 hook-like appearance in 2)uber than in holsatus, where they are practically 

 straight. As Cano pointed out, the Megalops of Carcinus may be distin- 

 guished from that of PortMiius, or Lupa, by the shape of the dactyl of the 

 fifth pereiopod. In holsatus (fig. 3) and puber (fig. 17) this joint ends 

 in a very short blunt claw, whereas in Carcinus the claw is long and 

 tapering. There are other characters by which these Megalopa can be 

 separated. In Carcinus the coxopodites of the second, third, and fourth 

 pereiopods have no long teeth. The Megalops of Carcinus is much smaller 

 than that stage in the two Portuni here dealt with. 



FiEST Young Stage. — Holsatus (fig. 13) has a very short rostrum; 

 puber (fig. 29) has a prominent triangular rostrum. The carapace of puber 

 is broader and bigger all over. Differences are also to be made out in the 

 character of the antero-lateral denticulations. 



Caecinus m^nas. 



The last Zoea (IV.) is shown in fig. 9. The pigmentation is charac- 

 teristic. 



Hyas areneus. 



The berried females of this species have at several times been kept alive 

 at the Laboratory in order that the Zoese might be obtained. Those that 



