STOMOPODA. MYSIDJE. 



GENUS THYSANOPODA, EDW. 



Generic character* External antenna, as in Mysis, inserted 

 beneath the internal, and furnished with a small antennal scale, 

 the basal joint broad and almost globular. Internal antennae in- 

 serted close beneath the eyes ; furnished with two filaments. 

 Pedipalps two pairs, entirely pediform, perfectly resembling the 

 legs themselves. Feet similar to each other and to the pedipalps, 

 excepting the last pair ; the basal joint short and thick ; the stalk 

 very long, and furnished with long hairs on the inner side ; the 

 palp short, lamellar, and hairy ; the last pair of legs much shorter, 

 consisting only of the palp, which is more developed. Carapace as 

 in Mysis. Abdomen with the lateral processes more developed 

 than in that genus ; the first five segments furnished with natatory 

 false feet the appendages of the sixth segment forming the lateral 

 caudal laminae, and the seventh constituting the central, slender, 

 and furnished at the apex with two needle-shaped appendages. 

 Branchial external, consisting of eight pairs, attached at the base 

 of the several pairs of thoracic natatory members ; the pedipalps 

 and true feet increasing in size and development from the first 

 to the last. They consist of a stem, or stalk, each furnished with 

 numerous lateral branches. Eggs contained in a pair of oval sacs 

 dependent from within the base of the posterior feet. 



This very remarkable genus of Mysidse was first de- 

 scribed by Dr. Milne Edwards, in the Anuales des Sciences, 

 from an Atlantic species which he found in the collection 

 of Crustacea formed by Mons. Reynaud, and placed in the 



* In the engraving at the head of the description of our species, are the detaiL 

 of all the essential parts ; for the beautiful and accurate delineation of which I 

 feel greatly indebted to Mr. Westwood's well known care and accuracy. 



