110 14 
For var. linter, E. Lamy gives the following distribution: — Nossi Bé, Isle of 
Bourbon, China, Macao. 
In the matter of synonymy I have followed Lamy with regard to navicularis 
as compared with linter, although I am of opinion that the latter is merely a 
variation of the former. In all the specimens from the Gulf of Siam the ligament 
upon the area had the form figured by Purxippi (loc. cit.) in Pl. III, Fig. 1. 
Arca Kraussi, Phil. 
Arca Kraussti, Poitier, Krauss, Die sidafrikan. Mollusken, 1848, p. 14, pl. 1, fig. 13. 
— _ — Abbild. u. Beschreib. neuer od. wen. gekannt. Conchyl., III, 1851, p. 88 (20), pl. 5, 
figs. 8—10. 
Koh Kram, 30 fathoms (1). Between Koh Mesan and Koh Chuen, 15—38 
fathoms, stones (2). Koh Chang, stones, very low tide (1). Koh Lom (1). Koh 
Mak, sand coast (‘/2). 
Long. 9—27 mm. (For comparison with the measurements quoted by LiscHKE: 
Jap. Meeres Conchyl., II, p. 142, I give the measurements of a specimen from between 
Koh Mesan and Koh Chuen. The length of the shell 27 mm., the height 15 mm., 
the length of the area 22 mm., the breadth of same 9 mm.). 
Distribution: — Mergui Archipel., Gulf of Manaar, Djibouti, Red Sea, Sey- 
chelles, Mascarenes, Querimba Isls., Natal. — Poulo Condor, Japan. 
The distinctness of this species has been much disputed. P. FiscHer! and 
A. H. Cooke? mention it as synonymous with A. Arabica, Forsk. (Phil.); KoBeir® 
believes it to be synonymous with A. maculata, Sow.; Ene. A. Smira* and E. Lamy? 
consider it to be identical with A. imbricata, Brug. (= umbonata, Lam., cuneata 
(cunealis), Reeve and Americana d’Orb.). G.B.Sowersy® identifies it with A. muta- 
bilis, Sow. Lamy in his latest revision of the species of Arca (Journ. de Conchyl., 
vol. 55, 1907, p. 28) identifies, and without doubt correctly, A. Kraussi, Phil. with 
A. imbricata, Brug. var. arabica Phil. 
The specimens from the Gulf of Siam agree closely with the description and 
figures of Krauss and Puinippi. Arca bicarinata, G.B. Sowerby‘ from Cebu (Philip- 
pines) is, no doubt, simply the present species. 
Arca signata, Dunk. 
(Pl. 1, Figs. 14—15). 
Arca signata, DuNKkrR, Novilates conchologicae. 1858 —70, p. 112, pl. 38, figs. 3—5. 
— - —~ Martini u. Coemnitz, Conchyl. Cabin., VIII, 2 Abth., pl. 44, figs. 7—8. 
— (Barbalia) signala, DuNKER, Lamy, Journ. de Conchyl., vol. 55, 1907, p. 78, pl. 1, figs. 1—2. 
1 Journ. de Conchyl., vol. XIX, 1871, p. 213. 
* Annals and Magaz. of Nat. Hist., 5. ser., vol. 18, 1886, p. 92. 
8 Marrini u. Coemnirz, Conchyl. Cabin., VIII, 2 Abth., pp. 76—78. 
‘ Challenger Expedition. Report on the Lamellibranchiata, p. 259. — Report on the zool. collect. 
made during the voyage of ‘Alert.’ p. 110. Proc. Zool. Soc. London, 1891, p. 431. 
® Bulletin du Muséum d'Histoire Naturelle, 1904, p. 271. 
® Marine shells of South Africa, 1892, p. 65. 
7 Proceed. of the Malacolog. Soc. London, vol. VI, 1901, p. 211, pl. 22, fig. 14. 
