BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 11. N:0 9. 5) 
Thaumatops. R. Vv. WILLEMOES-SUHM. 
Syn. 1842. Cystisoma. F. GUÉERIN-MENEVILLE, 1. c., p. 215. 
1852. > > JAI. DANAS I Cr pr o8k 
and 1442. 
1862.  Cystosoma. > C. SPENCE-BATE, 1. c,, 
Pp: all. 
1874. Thaumops. BR. VON WILLEMOÉS-SUHM, Phil. Trans. Roy. Soc. 
vol. 163, part. 2, pag. 
629 and 638. 
1875. Cystisoma. GUERIN-MENEVILLE, R. VON WILLEMOEsS-SUHM, 
: Trans. Linn. Soc., ser. 
II, Zool., vol. 1, part. 
Tp vad 
Diagn. "The body is hyaline, the segments distinctly separat- 
ed from one another (except the two first pereional segments of 
Th. Neptunus and Th. pellucida, which are coalesced). The 
epimerals are only indicated. 
The head is large, more or less rounded, tumid. The 
eyes are large occupying almost all the upper surface of the head. 
Only the first pair of antenne are developed, straight, 
few-articulated. The second pair are represented by two 
small tubercles. 
The mandibles are small, rounded, with a molar tubercle, 
but without palp. 
The second pair of maxzille consist of only one lamina 
The first and second pairs of peretopoda are cheliform, 
the following ending with a claw-shaped dactylus. 
The uropoda are very thick, the second pair wanting, the 
inner rami coalesced with the peduncles. 
The animals belonging to the genus Thaumatops are true 
pelagic forms, just as their nearest relatives, the Mimonec- 
tides and the Phronime. They åre the largest of all Hype- 
rids. The enormous size seems rather to be needed in order to 
support the animal floating, than for any other purpose, as a 
considerable part of the interior of the body forms a vesicle 
filled with some fluid; but the body itself is of normal 
structure and not balloon-shaped as in Mimonectes. 
At present it seems fit to divide the genus into four 
species. 
