TRUMPET-SHAPED EYES 273 
thin, narrowly conical, ending in a single long seta. This 
process is not met with in any other genus. The telson 
is not incised at the apex. ‘There is only a single species 
known, Macropsis Slabberi (van Beneden), first described 
by Slabber, as a shrimp with trumpet-like eyes. It belongs 
to British and most other Huropean coasts. Slabber was 
not a little struck by its organisation, and van Bene- 
den improves the occasion by observing that in a steam- 
engine on a railway we admire the marvel of human in- 
dustry that has contrived its complicated parts, but that, 
if such a locomotive were comprised in a grain of sand, if 
we could see several of its kind deploying with precision 
in a drop of water, we ought to be far more excited to 
astonishment and admiration. 
Heteromysis, of which the type is the American, British, 
and Norwegian species, Heteromysis formosa, 8. 1. Smith, 
is distinguished from almost all other Mysidee by having 
the pleopods rudimentary in the male as well as the female, 
and also by having the third maxillipeds much stronger 
than the rest of the legs and ending in a sort of subchelate 
finger, which induced Sars to call the genus Chiromysis, 
‘the Mysis with a hand,’ before he knew that it had been 
otherwise named by Professor Smith. The telson is in- 
cised. 
Mysidella is said to stand nearer to Heteromysis than 
to any other genus, but with the first instead of the 
third maxillipeds strongly built and peculiar. It has the 
body short and stout, the scale of the second antennz 
small, obtusely lanceolate, and fringed with hairs on both 
margins. The upper lip is obtuse in front, and deeply 
incised behind ; the mandibles have a large cutting plate 
which is quite simple, without any teeth. The legs are 
small and weak, the genital appendages of the male being 
very elongate. ‘The pleopods in the male have the same 
rudimentary structure as in the female. The telson is 
short, not deeply incised, and finely aculeate on the hinder 
portion of each lateral margin. It includes the two Nor- 
wegian species, typica and typhlops, of Sars. 
Mysidopsis has the scale of the second antenne fringed 
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