251 



P. villostilns Qtwénw^). See also the present paper, p. 255. Literature : Miers, Rep. "Challenger", 

 Brachyura, 18S6, p. 277, pi. 22, f. 2; Burger. 1. c, p. 366, pi. 10, f. 5. Hab. 

 Timor, Torres Straits, Philippines. In Meleagrina. 



P. villosissiimts Doflein, Wiss. Erg. "Valdivia" Exp., Bd 6, Brachyura, 1904, p. 125, pi. 37, 

 f. 5 — 6, te.xtfig. II. Hab. Padang. In the Holothurian MucIIeria Iccanora. 



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 

 livino- in the cloaca or the "lunCT" of Holothurians. 



P. jïavus Nauck. 



P. lioIotJiuriac Semper. In Stichopiis varicgatits. 



P. pihunnoides Nobili. In Holothuria gallensis (also in sponges). 



P. scinperi Burger. In HoIotJiuria fusco-cincrca. 



P . tenuipes Burger. 



P. villosissiiniis Doflein. In Miiellcria lecanora. 



One species, P. dofleini Lenz et Strunck, is found in an Ascidian, Phallitsia canaliciilata. 

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

 common type in Pinnot/icrcs, inasmuch as the dactylus is spoon-like, not styliform. 



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

 The following species I have not included : 



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



P. placitnae Hornell et Southwell, 1 



. . > the descriptions of which are inaccessible to me. 



P. rtdgewayi Southwell, ) 



Furthermore I have omitted the New Zealandian species : 



P. pisjiiu (Linné), 



P . Hovae-selaiidiae Filhol, 



P. sckaitinshindi 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. INIostly 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 veferred to by H. Mii.ne-Edwards and Burger undev the name villnsus. I cüuld not consult Giiérin's 

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

 species is named vi/losu/us^ whicli teim is used by Miers. 



103 



