CRUSTACEA. 
285 
three teeth above. The antenurc reraain in the same state. The 
eyes have lost the small appendage that was attached to them in 
the last form. The central eye has almost disa])peared. The 
mandibular appendage has become two-jointed; and other 
changes characteristic of the adult animal have taken place. The 
animal at this period — the largest that has been examined — has 
attained the length of from 9-10 mill. 
In a short appendix^ Dr. Muller describes the forms of the 
larvfe of two or three otlier species, and announces one of so 
different a progressive morphology as to induce him to take 
some future opportunity to describe it. 
Euphausid^. 
In the ‘^Ann. and Mag. of Nat. Hist./ vol. xiv. 1864, p. 461, 
and the ^ Archiv. des Sci. Phys. et Nat.,^ tom. xxi. p. 87, 
is a short notice of the description of Lopliogaster typicus 
published by Prof. Sars in 1862. This Crustacean is an excep- 
tional form, and holds an intermediate position between the 
Stomapoda and Macrura. This is shown in the nature of the 
branchial organs, which are branched like the posterior branchiae 
of the Euphausidae. The upper part of the ramification is covered 
by the carapace, as in the Macrura, whilst the median and 
lower branches hang down freely in the water, as in the Euphau- 
sidae. It is therefore argued by the author that the Stomapoda 
are but degraded forms of the same order as the Alacrura. The 
development of the young of Lopliogaster is precisely similar to 
that of Mysis. 
Mysida?. 
% 
Prof. Sars describes several Norwegian species of the genus 
Thysanopoda (Om Slaegten Thysanopoda og dens norske Arter. 
Forh. Vidensk. Selsk. Christ, (aar. 1863), 1864), first giving a 
full description in Latin of Thysanopoda norvegica (Sars), wliich 
he had previously described (Forh. Skand. Naturf. i Christiania, 
1856, pp. 169-174). 
In tliis description Prof. Sars says that the eighth pair of tho- 
racic feet are rudimentary. We really are at a loss to know 
what appendages these can mean ; we must assume them to be 
the posterior pau’ of pereiopoda, because they are the last de- 
scribed; but we think that there must be some mistake in 
dcsciibing in a Decapod Crustac('.ati ciglit pairs of limbs as be- 
longing to the pereion. Tliat Prof. Sars has not counted the 
appendages of the cephalon is quite clear; for in his description 
of Thysanopoda norvegica he mentions the first six pair of the 
appendages of the pereion (pedes thoracici) after the (maxilli- 
pedes), and these after the second pair of siagonopoda (maxilla 
secundi paris). This is giving to these Norwegian Thysanopoda 
a pair of appendages more than belongs to this order of Crustacea. 
In his description he gives a full account of the form and 
