251 



p. viHosiihis Gu€r'm'^). See also the present paper, p. 255. Literature: Miers, Rep. "Challenger", 

 Brachyura, 1886, p. 277, pi. 22, f. 2; Burger, I.e., p. 366, pi. 10, f. 5. Hab. 

 Timor, Torres Straits, Philippines. In Meleagrina. 



P. vi/Iosissimzts Do^em, Wiss. Erg. "Valdivia" Exp., Bd 6, Brachyura, 1904, p. 125, pi. 37, 

 f. 5 — 6, textfig. II. Hab. Padang. In the Holothurian Rhielleria lecanora. 



In the foregoing list 65 species are enumerated. The vast majority of these, as far as 

 the host is known, inhabits the mantle-cavity of Lamellibranchs, but the following species are 

 living in the cloaca or the "lung" of Holothurians. 



p. jlavtis Nauck. 



P. holothuriae Semper. In Stichopiis variegatus. 



P. pilumnoides Nobili. In Holothtiria gallensis (also in sponges). 



P. seinperi Burger. In Holothtiria ftisco-cinerea. 



P. temiipes Burger. 



P. villosissiunts Doflein. In Muelleria lecanora. 



One species, P . dojieijii Lenz et Strunck, is found in an Ascidian, Phalhisia canaliculata . 

 The external maxillipeds of these species, in the majority of cases, deviate from the 

 common type in Pinrwthcrcs, inasmuch as the dactylus is spoon -like, not styliform. 



In preparing a key to the species Burger's synopsis has proved to be of much use. 

 The following species I have not included : 



P. doninensis Stimpson, on account of the imperfectness of the description. 



P. plactinae Hornell et Southwell, ) , , . . . , . , 



\ the descriptions of which are inaccessible to me. 

 P. ridgewayi Southwell, ) 



Furthermore I have omitted the New Zealandian species : 



P. pisnm (Linne), 



P. novae-zelandiae Filhol, 



P. schauinslandi Lenz. 

 Key to the species : 



1 . Dactylus of ext. maxillipeds inserted at inner margin of propodus. 2 

 Dactylus of ext. maxillipeds placed nearly at end of propodus 



and reaching much farther 53 



2. Dactylus styliform 3 



Dactylus spoon-like, widening distally. Mostly in Holothurians . 46 



3. Dactyli of all the walking legs subequal in length 4 



Dactyli of the walking legs unequal in length 17 



4. Dactylus of ext. maxillipeds overreaching propodus .... 5 

 Dactylus of ext. maxillipeds not overreaching propodus ... 7 



i) This species is referred to by H. Mh.ne-Edwards and Burger under the name villosus. I could not consult Guerin's 

 original description in Voy. "Coquille", t. 2, 1830, p. 13, but in his subsequent work (Iconogr. Regne An., Crust, p. 7, pi 4, f. 4) the 

 species is named villosnhis^ ■nhich term is used by Miers. 



103 



