186 
3die Leri lain Inlet udvidet bagtil, Hofteleddet pcaa de 2 
bagerste Par ovalt. Sidste Par Halefodder simple, uden 
laterale Tomer. Halevedhamget simpelt, tilrundet. Legemet 
gjennemsigtigt, med kun sparsomt rodligt Pigment. Lseng- 
den indtil 14“”. 
Findesteder. Stat. 31, 343. 
Bemserknmger. Denne Art staar vistnok meget nser 
M. Aider!, Sp. Bate, med bvilken jeg ogsaa ferst identifi- 
cerede den, men viser dog, som jeg senere har overbcvist 
mig om, tilstrsekkelige Afvigelser til at maatte opfattos som 
on distinct Art. Foruden ved den langt betydeligere Stor- 
relse kjendes deu strax ved den sserdeles uligo Udvikling 
af de 2 Par Folere, tier forholder sig fuldkommen ens hos 
begge Kjon, medens disse ialfald hos Hunnen af At. Alder i 
er omtrent af ens Lasngde; fremdeles ved Formen og Be- 
vaebningen af 2det Fodpars Haand, endelig ved det bagtil 
mindre stajrkt udvidede 3die Led paa de bagre Fodpar. 
Beskrivelse. Legemet er (se PI. XV, Fig. 4) af 
forholdsvis mindre underssetsig Form end hos de ovrige 
bekjendte Arter af Slsegten og noget sammentrykt fra Si- 
derne, med rund, buet Ryg og tynde gjennemsigtige In- 
tegumenter. 
Hovedet er forholdsvis lidet og har Sidolijornerne tem- 
melig staerkt fremspringende mellem Roden af de 2 Par 
Folere, saint smalt tilrundede. 
Af Epimererne er det lste Par som saedvanlig ganske 
rudimentmrt og fuldstamdig dsekket af det folgende Par. 
Dette er af elliptisk Form og skjfevt fortilrettet. 3die Par 
er aflangt 4-kantet og omtrent dobbelt saa licit som Krop- 
pen. 4de Par er omtrent saa stort som begge de 2 fore- 
gaaende tilsammen og af afruiulet triangular Form, bagtil 
smalt tilrundet og dsekkende fuldstamdig Basis af 5te Fodpar. 
De 3 forreste Bagkropssegmenter har Sidepladerne 
forholdsvis lidet udviklcde og dannende bagtil et stumpt 
Hjorne. 
0inene er meget smaa, runde, med Pigmentet, tier er 
af rod Farve, kun indtagende den centrale Del. 
Lste Par Folere er forholdsvis meget smaa og tynde, 
med Skaftets lste Led omtrent dobbelt saa langt som 2det, 
og sidste Led sserdeles lidet. Svoben er omtrent af Skaftets 
Laengde og sammensat af omkring 20 korte Led. 
2 det Par Folere er derimod sserdeles kraftigt uclvik- 
lede og nsesten dobbelt saa lange som lste Par, med Skaftet 
meget staerkt, cylindriskt, hvorimod Svoben er ualmindelig 
liden og tynd, kun dannende et smalt snaertformigt 7-leddet 
Appendix til samme (se Fig. 4 a). 
Overlaeben (Fig. 4 b ) danner en liden paatvaers ellip- 
tisk og i den nedre Kant noget indbugtet bevaegelig Lap. 
ceolate. The 3 hindmost pairs of legs with 3rd joint but 
slightly dilated posteriorly, basal joint oval on the 2 pos- 
terior pairs. Last pair of caudal stylets simple, without 
lateral spines. Telson simple, rounded. Body translucent, 
and but sparingly furnished with pigment, of a reddish 
colour. Length reaching 14”"". 
Locality. — Stat. 31, 343. 
Remarks. — This form approximates, it is true, very 
closely M. Alder i Sp. Bate, with which indeed I first held 
it to be identical ; meanwhile it exhibits, as I subsequently 
found, sufficient deviating characteristics to warrant our 
regarding it as a distinct species. Let alone the far greater 
size, it can immediately be recognized by the very unequal 
development of the 2 pairs of antennae — perfectly uniform 
in both sexes; whereas the antennae (in the female of M- 
Aider! at least) are about equal in length; moreover, by the 
armature characterizing the hand of the 2nd pair of legs; 
and finally, by the 3rd joint of the hindmost pairs of legs 
being less dilated posteriorly. 
Description. — The body (see PI. XY, fig. 4) is 
comparatively less thickset in form than in any of the other 
known forms of the genus, and somewhat compressed from 
the sides, with a round, arcuate back and thin, translucent 
integuments. 
The head is relatively small, and has the lateral 
corners narrowly rounded and projecting a good deal be- 
tween the bases of the 2 pairs of antennae. 
Of the epimera, the 1st pair are as usual quite rudi- 
mentary, and wholly covered by the 2nd. The latter are 
elliptic in form and point obliquely forward. The 3rd pair 
are oblongo-quadrate, and well-nigh double the height of 
the body. The 4th pair are about as large as both the 
2 preceding ones taken together, and rounded-triangular 
in form; posteriorly rounded narrowly off and covering the 
whole base of the 5th pair of legs. 
The 3 anterior abdominal segments have the lateral 
plates comparatively slight in development, and forming 
posteriorly an obtuse corner. 
The eyes are very small, round, with the pigment of 
a red colour, occupying the central part only. 
The 1st pair of antennae are comparatively very small 
and slender, with the 1st joint of the peduncle about twice 
as long as the 2nd and the last joint exceedingly small- 
The flagellum is nearly equal to the peduncle in length, and 
composed of about 20 short articulations. 
The 2nd pair of antennae, on the other hand, are 
most powerful in development, and well-nigh twice as long 
as the 1st, with the peduncle very strong and cylindric, 
whereas the flagellum is remarkably small and slender, 
forming merely a lash-like seven-jointed appendix (see fig- 
4 a). 
The labrum (fig. 4 b) consists of a small, transversely 
elliptic, and, along the lower margin, somewhat incurved, 
movable lobe. 
