24 
THE YOYAGE OF H.M.S. CHALLENGEK. 
while the genus Squilla is restricted by him to those species which, with a similar 
raptorial claw, have longitudinal carinse on the carapace and hind body ; the eyes not 
constricted at the tips ; the carapace elongated, and the appendages of the thoracic 
limbs slender and styliform. 
The forms which he includes in the genus Chloridella are certainly less specialised 
than the higher Squilla?, but the Challenger collections show that they are connected 
with the latter by intermediate forms in such a way that it is impossible to draw a line 
between them, and that they do not form two divergent branches, but a single series. 
Squilla lata, n. sp. (PI. III. figs. 1, 2, 3), is a Squilla, according to Miers’s definition, 
while Squilla chlorida, n. sp. (PL II. figs. 1-5), is a Chloridella, but Squilla fasciata 
(PI. III. figs. 4, 5) is so very similar to both of these species that it is very hard to 
distinguish from them, and it is intermediate between them in respect to the very 
characteristics upon which 'Miers bases his genera. We must therefore enlarge the genus 
Squilla to include the Chloridellse. 
Ontogeny. — The Alima larva is one of the most sharply defined larval types, and we 
have every reason to believe that all the larvae in this group pertain to closely related 
adults. As one of them has been kept by Faxon in an aquarium until it changed into 
a young Squilla, and as all the species of the genus Squilla agree with each other in 
several features which are not united in any other adult Stomatopod ; the flatness of the 
hind body, the small number of marginal spines on the dactyle, the great number of 
secondary spines on the telson between the intermediate and the submedian marginal 
spines, and the greater length of the inner one of the two spines on the basal prolongation 
of the uropod ; and as all the Alima larvae, including Alimerichthus, agree with each 
other, and differ from all other Erichthidae except the anomalous Erichthalima, in 
similar features, we can state with confidence that all Alima larvae are young Squillse, 
and that all Squilla larvae are Alimse. 
While the Alima is a highly specialised larva it is, in a certain sense, embryonic, for 
the fully grown Alima closely resembles the young Lysioerichthus larva, as may be 
seen by comparing fig. 4 of PI. I. with fig. 5 of PI. XII. The Erichthus, in some 
cases and probably always, hatches from the egg as an Eriehthoidina, while it is 
probable that all the Alimse leave the egg in the Alima stage ; but this is so similar to 
the young Erichthus that Claus was disposed to regard his Erichthus multispinosus as 
an Alima, although the fully grown Erichthus is very different from the Alima at any 
stage of its development. Apparently the stage which the Lysioerichthus passes 
through, immediately after the Eriehthoidina stage, has proved to be so well adapted to 
the needs of the Squilla larva that it has been lengthened at both ends of the larval 
life until both the initial Eriehthoidina stage and the final Squillerichthus stage have 
been crowded out of its larval life, and the Alima hatches as an Alima and remains an 
Alima, until it changes into a Squilla. 
