KONGL. SV. VET. AKADEMIENS HANDLINGAU. BAND. 22. N:0 7. 365 



In 1868 Spence Bate and Westwood gave tlie following »speciiic cliara,ctcr«: 



»Cheliform organ on the third pair of pereiopoda slender. The inner margins of each 

 rauuis of the chela furnished with one tubercle, both tubercles finely tuberculated.» 



In 1872 Claus gave the first drawings of a male form of Phroniina, and in 1879 

 be, as uientioned above, publisbed most valuable anatoraical details of Phroninia seden- 

 taria and its allies. 



In 1875 PowELL proposed the new speciiic name Phronima novce-zealandice, which 

 howevei" must be considered a synonym for Ph. sedentaria, as there are no important 

 ditferences in the Australian specimens, which I have examined, from the Mediterranean 

 specimens of the true Ph. sedentaria. The diagnostic points which he mentions, viz; 

 »The long sharp process on the mera of the second pair of gnathopoda, the processes on 

 the basa and ischia of the third pair of ])ereiopoda)), as well as the characteristics given 

 in his description, agree with Phronima sedentaria. 



In 1888 Stebbing with some hesitation identified with Fhroniriid novce-zealandiw a 

 specimen, which, in my opinion, is a true Ph. sedentaria. 



Phronima sedentaria is closely allied to Ph. atlanticn, Ph. solitaria, and Ph. 

 spinosa; it differs from them all in the more elongated form of the carpus and the car- 

 pal process of the fifth pair of pera3opoda, and in the long, sharp projection from the 

 hind corner of the last pleonal segment. From Ph. atlantica especially it is distinguished 

 in the female by the undivided tubercle on the under margin of the carpus of the fifth 

 pair, and in the male by the carpus of the same pair being much longer than broad; 

 from Ph. solitaria again by the well developed tubercle on the front margin of the meta- 

 carpus of the fifth pair; and from Ph. spinosa by the form of the femur of the same pair. 



The newly-hatched young have all the seven pairs of pertEopoda developed and of 

 nearly the same length; the carpus of the fifth pair is distinctly dilated but still longer 

 than broad. The lower front corner of the carpus is at first bi'oadly rounded, then grows 

 angular, and lastly projects into a sharp-pointed process; this process is much longer in 

 the young female than in the young male. 



The females seem to grove much larger than the males; the largest female I have 

 examined measured 36 mm. from the front margin of the head to the apex of the last 

 pair of uropoda, while the largest male attained only 16 mm. 



The question of the nature of the »house» of Phroninia has been ventilated al- 

 most from the description of the first specimen of Phronima sedentaria, and thoroughly 

 examined by Pagenstecher, Claus and Mayee. It seems beyond doubt that it in most 

 cases consists of the rests of Tunicata and Siphonophora, which have been attacked, and 

 adapted for its purpose, by the Phronima itself. 



