40 CARL BOVALLIUS, AMPHIPODA HYPERIIDEA. I. 2. THAUMAT0PSID7E. 



which he woulcl call Cystosomidce. In the above cited paper I proposed the name Thau- 

 matopsidae for the faraily, it being unfit to einploy a family name which is not deri- 

 ved from a generic name in use within de family, and when Cysteosoma, Cystisoma or 

 Cystosoma was justly rejected as being preoccupied, I could not maintain the proposed 

 name Cystisomidce or rather Cystisomatiche, as it ought to have been written. Th. Stebbing, 

 however, regarded my reasons for rejecting the old name as not valid, and restored both 

 the naraes viz; Cystisoma and Cystisomidce, presuming that ethyraological correctness is not 

 needed in writing zoological names, and that the diffei^ence between Cystisoma and CystO- 

 soma is sufficient to allow the keeping of both alive, although both really are the same name. 

 I cannot but oppose this opinion and still believe that each genus must have a name by 

 itself, orthographically wi-itten. Therefor I still retain the names Thaumatops and Thauma- 

 topsidaä. 



The biological notices about the members of the family are very meagre. We onlj 

 kno^v that the most of the very few hitherto reeorded specimens, the seven captured du- 

 ring the Challenger Expedition, have been dredged from a depth varying from 500 to 

 2500 fathoms; the previously known specimens were taken floating on the surface of the 

 sea, as far as I could ascertain. 



The enorraous size of the body seems to be in some wa}' connected with the ani- 

 maVs power of floating and diving, as the most of the interiör of the body is occupied 

 by a kind of vesicle filled with some fluid. It is very pi-obable that the animal possesses 

 means to change its speciiic gravity by compressing or dilating the vesicular room thus 

 increasing or diminishing the amount of fluid in it, but I have not been able to detect 

 neither muscles on the walls of the vesicle, iior any outlet from it. 



i4s to their geographical distribution, they must be considered as chiefly tropical or 

 subtropical animals, they are, however, widely spread out över the surface of the seas and 

 probably more widely than most of the other Hyperids owing to their stx-ongly developed 

 floating powers. 



Hitherto the family contains only one genus. 



Genus 1. THAUMATOPS, R. von WILLEMOES-SUHM, 1873. 



Diagii. Ccqjut plus minusve splifericum. Antennce secundi paris tiibercula minima formant. Peden 

 percei prirai et secimtli paiium cheliformes. Ejiimera indistincta. Pedes uri crassi, ramis 

 internis cum pedunculis coalitis; pedes seciuidi paris desunt. 



The head is more or less spherical. The second pair of antfnnw form very small tubevcles. 

 The first and second pairs of perreopoda are cheliforin. The epimirals are indistinct. The 

 urupoda are thick, prismatic; the inner rami are coalesced witii the corresponding pedun- 

 cles; the second pair are wanting. 



