NO. 1480. SCHIZOrOD CnVSTACEANS—OIlTMANN. 43 



the posterior margin. Epimera of the five anterior segments, witli 

 the anterior lappet small, the posterior produced and aciitel}^ pointed. 

 There is, on each segment, an indistinct subdorsal keel on each side. 



Epimera of sixth abdominal segment of the type of the second group, 

 formed by onh' one triangular, acute lappet on each side of the ante- 

 rior section of the segment, and not forming a ventral plate. 



The only difference of the variety sarsi from the t3'pical form is 

 found in the shape of the lamellar expansion of the postero-inferior 

 angle of the carapace: in the t3"pical form, this expansion is rounded 

 off', while in the variety it is rectangular. It is possible that the latter 

 character is only restricted to the voung, and that it generally disap- 

 pears with advancing age, but then it would disappear at different 

 stages in different individuals, in the average, when they are about 

 lialf grown (see below). 



The identity of G. zoea and G. nullemoesi. — I have devoted much 

 time to the study of the differential characters of these two species, 

 as determined by Sars (1885), pnd have the following to say with ref- 

 erence to them: 



In Sars's synopsis of the species (p. 29), the length of the postero- 

 dorsal spine is paramount: it is "greatly produced" in 6^. .3y>/V/, and 

 "comparatively short'' in G. unlJeinoesL 



The differences between the species, taken from Sars's diagnosis and 

 description (pp. 38 and 4'1) are the following: 



1. The length of the postero-dorsal spine just mentioned: in G.soea 

 this spine reaches sometimes beyond the fourth abdominal segment, 

 while in G. irilJemoesi it is onl}^ slightl}^ longer than the first abdomi- 

 nal segment. 



2. The posterior margin of the carapace, and the margins of the 

 postero-dor.sal spine are "coarsely denticulate" in G. zoia^ and 

 "decidedly glabrous" in G. inillemoesi. 



3. The rostrum is very elongate (even exceeding the carapace with- 

 out posterior spine), and strongly denticulate in G. zoea; it is shorter 

 than the carapace, and provided with small, comparativeh" few, den- 

 ticles in G. wiltenwesL 



4. The spme of the antennal scale projects somewhat beyond the 

 terminal lobe of the lamellar part, and is slightly denticulate at the 

 outer edge, in G. zoea/ it is a little shorter than the terminal lobe, and 

 not denticulate, in G. wille7noesi. 



Discussing these four points in detail: 



1. Sars seems to lay nuich stress upon this character. I have shown, 

 however, in several of the foregoing species, that the relative length 

 of the spines of the carapace changes with age, being generally longer 

 in young individuals. As regards the present case, G. zoea is founded 

 upon specimens much younger than those of G. ivillenioes!. More- 

 over, I have extracted embryos from the marsupial pouch of a large 



