638 ON THE MALE AND TITE STKUCTUKE OF THAUMOPS PELLUCID A. 
to the oral apparatus, and the second giving rise to a peculiar organ which consists of 
tw T o chitinous claws united by a thin layer of the same substance, so as to form a sort of 
plate. I have already mentioned that I am not quite sure whether this is a labium or, as 
it seems more probable, the result of the displacement and union of the second maxillae. 
This organ is situated at the inner side of the maxillipedes, the third joint of which 
consists of two strongly denticulated and separate claws. The two appendages (Plate 
XLIX. fig. 1, mx) which I first thought act as maxillae are the gnathopoda of Spence Bate, 
followed by five pairs of pereiopods. The pleopods or swimmerets consist in the male, 
as well as in the female, of only three pairs. 
All the other particulars described in the female may also be found in the male. 
The question now arises whether the systematic position which I assigned to Thaumops , 
as a representative of a new family of Hyperidce , to be placed next to the Plironimce , 
can still be maintained. After having carefully examined the question, I think it 
not only can but must be maintained. As Professor Claus was kind enough to write 
to me, and as I had remarked already before getting his letter by studying living 
specimens of Oxycephalus , there are several points by which Thaumops approaches the 
Typhidce , especially the elongate shape of the head, with the mouth underneath and the 
claws terminating the gnathopods. On the other hand, however, the want of the 
second antennae in the male, the elongate slender shape of its first antennae, which show 
nothing of the enlargement and the olfactory hairs peculiar to the male Typhidce , and the 
want of the palpus in the male mandible, show that it differs widely from the Typ>hidce. 
I therefore think that the position I first proposed for this animal is the right one. 
The characters, however, which I assigned to it must be changed somewhat in the 
following way. 
Thaumops, nov. gen. 
Caput oblongum, oculis maximis superiorem capitis partem tegentibus. Segmenta 
thoracica septem, abdominalia quinque. Antennarum in utroque sexu par unum. 
Mandibulse et maxillse minimse. Maxillipedum par unum conjunctum. Pedum 
thoracicorum paria septem, anteriora duo parva et chelis armata. Pedum abdo- 
minalium paria tria. 
Thaumops pellucida, n. sp. 
Corpus longitudine 84-103 mm. In maris Atlantici parte septentrionali. 
There is no doubt that Thaumops is a pelagic crustacean ; and it is probably spread 
all over the Atlantic, for we got it off the coasts of Portugal and very near the equator. 
It was caught once at night in the towing-net and three times by the trawl, coming up 
from a great depth ; therefore it seems probable that, like many other pelagic animals 
which in the daytime live in a depth of 40-100 fathoms and come up only in the night, 
it retreats to a considerable depth ; and this is probably the reason why it has so long- 
remained unknown. 
II.M.S. 1 Challenger ,’ Bahia , September 1873. 
