51 147 



young, were diuk-coloured, quite an individual character. In the new edition of 

 "Mautini & Cm.MNiTz, Conchy]. Cabinet, " Clessin has worked oui the genus Perna,^ 

 but nowhere does he mention Chemnitz's P. Spengleri. 



Perna isognomon, L. 



Oslrea isognomon, Linnk, Syst. Nat., ed. X, 1758, p. (599, No. 17G. - ed. XII, p. 1U9. Mus. Ludov. Ulr., 



p. 533, No. 120. 

 Melind Isoijomint, — tÎKXziiis, Nova Tcstaccor. Gen., 1788, p. 23. 

 Ostrea isognomon, — Gmelin, Syst. Nat., ed XIII, p 3338, No. 125. 

 Perna {.•iognomiim, — Rkeve, Coiichol. icon., XI, Perna, Sp. 24. 



— isogonum, — Ci-essin in Martini u. Chemnitz, Concliyl. Cabin., VIII, 1 Abtli., ))]. 8, fig. 1. 



East of Koh Chuen, 9—10 fathoms, shells (2). 



Distribution: — Singapore, Mergui Archip., Madras, Madagascar and Mozam- 

 bique, Mauritius. — Poulo Condor, Philippines, Amboina, Moluccas, Sorong, New 

 Guinea, Thursday Isl. 



Of the two specimens brought home from the above-mentioned locality the 

 larger (long. 59 mm., alt. 99 mm.) should be referred to the variety femoralis, Lam.,^ 

 and the smaller (long. 34 mm., alt. 73 mm.) to the variety curvata, Ch.-' 



Perna rudis, Reeve. 



Permi rnilis, Reeve, Conchol. icon., XI, Perna, Sp. 20. 



— — — Mautini u. Chemnitz, Conchj'I. Cabin., VIII, 1 Abth., p. 31, pi. 9, fig. 6. 



North end of Koh Chang, 1 fathom, old coral blocks (1). Koh Kahdat, 1 

 fathom, sand (3). 



Alt. 14-98 mm. 



Distribution: — Jousseaume' records that one specimen of this species 

 was taken at Obock (Gulf of Aden). Collected by Vokltzkow at Zanzibar. 



The present species is closely allied to P. isognomon L. A. H. Cooke'' thinks 

 that P. rudis, Reeve, is synonymous with P. legunien, Gmel. (= linguaeformis, Reeve 

 = laticostata, Reeve = caudata, Reeve). 



Perna Cumingi, Reeve. 



Perna Cumingii, Reeve, Conchol. icon., XI, Perna, Sp. 3. 



Cnmingi, — Martini u. Chemnitz, Conchyl. Cabin., VIII, 1 Abth., p. 40, pi. 15, iig. 1. 

 Melina cumingii, — Edg. Smith, Zoolog. Collect, of H. M. S. "Alert," p. 113. 



' The extremely unsatisfactory and unscientific way in wliich this has been done is much to be 

 regretted. As an example of the superficiality which chai-actcrises the worli may be mentioned that 

 one of the best-known species, P. isognomon L., is called P. isogonum L tliroughout the whole work. 



- Hist. nat. d. anim. s. vert., 2 éd., VII, p. 76, No. 5. 



» Chemnitz, Conchyl. Cabin., VII, 1784, p. 256, pi. 59, fig. 583. 



■• Mém. de la Soc. zoolog, de France, 1, 1888, p. 219. 



° Annals and Magaz. of Nat. Hist., 5 Ser., vol. 17, p. 138. 



19" 



