65 



dredging in the Western entrance of the Samau Strait (St. 59). Both the shells are very young 

 and are greatly weathered, and it is not possible, therefore, to be absolutely definite about their 

 identification ; in gênerai form and sculpture, however, they resemble Reeve's spécimens of 

 G. temdcostahis. 



6. Glycymeris hoylei (Melvill & Standen). 



1899. Pectimcidus Hoylei Melvill & Standen, Journ. Linn. Soc. London, (Zool.), XXVII, p. 187, 



pi. XI, fig. 24. 

 1906. Glycymeris cardiifo7-viis Hedley (nec Angas), Proc. Linn. Soc. N. S. Wales, XXVI, p. 470. 

 1909. Pectîinculus Hoylei Melvill, Trans. Linn. Soc. London (Zool.), XIII, p. 123. 

 19 12. Pectunculus Hoylei Lamy, Journ. Conchyliol., LIX, p. 93. 



Hedley's record of G. cardiiformis (Angas) from the Mast Head Reef, Australia, is, as 

 Lamy was able to confirm by an examination of Hedley's spécimens, based on shells of G. hoylei 

 (Melvill & Standen). 



Distribution: — G. hoylei was originally described from the Torres Straits, and has since 

 been recorded from the Indian Océan. 



In the "Siboga" collection there are a number of young and rather worn shells from the 

 Western Entrance, Samau Strait (St. 59), St. 63 (7° 37^.2 S., i22°3^5E.), Bornéo Bank (St. 80), 

 and St. 95 (5°43'.5 N., ii9°4o'E.). Ail thèse spécimens I hâve compared with the types of 

 the species in the British Muséum, London, and can find no différences either in the form or 

 the sculpture. 



7. Glycymeris dautzenbergi sp. nov. (Plate II, figs. 15 — 18). 



The following is a description of this nevir species : — Species of a small size ; shell about 

 as long as high, rather flat, rounded, solid; umbones prominent, full, subcentral; sculpture 

 consisting of 23 almost equally spaced radial ribs, on young shells and younger parts of adult 

 shells closely placed and separated by shallow and thin furrows, those in adults broaden out to 

 interspaces almost as broad as ribs near the distal margin; concentric sculpture consisting of 

 fine, but deep striae, w^hich eut up the radial ribs into rounded to ovoidal nodules, near the 

 margin in adult shells lower nodules are often eut up into two by the channeling of the radial 

 ribs; cardinal area narrow, not deeply excavated, extending almost equally in front of and 

 behind the umbones ; hinge-plate moderately broad, furnished with 9 — 10 oblique denticles 

 arranged in a curved séries on each side and connected by 6 — 7 vertical teeth in the middle. 

 Muscle scars not deeply scalloped at the edge and armed internally with 16 broad denticles of 

 inverted triangular shape. Interior of shell glossy white with splashes of brown below and around 

 the muscle-scar areas, periostracum uniform dirty white. 



Measurements (in millimètres) 



Length 8 10.2 12.2 19.6 



Height 7.8 9.8 12 19.3 



Diameter 4.3 5.4 7.2 10.8 



Habitat: — Two young shells of this interesting species were dredged by the "Siboga" 



SIBOGA-F.XPEnTTTF. LIII<r. 9 



