63 



in his description is not présent in the young shells, while the ribs on the area in front of the 

 umbones are distinctly grooved ; the fine concentric threads running crosswise to the radial ribs 

 are well marked in young shells and on the marginal région. In view of no measurements of 

 the species having been published, I give below the measurements of four shells from the 

 "Siboga" collection and two from the Island of Capul in the British Muséum Collection. 



Measurements (in millimètres) 

 Length .... 13.2 22.7 29.2 47 50 49 



Height .... 13.6 21.4 28 51 55 55.3 



Diameter . . . 8.8 11.7 17.3 29.2 32 34 



Distribution : — The species has so far been recorded from the Philippines only. 

 In the "Siboga" collection it is represented by a single young shell trawled off Banda 

 Anchorage (St. 240), two stray valves of young shells collected at Banda at a depth of 9— 45 mètres, 

 and 3 shells dredged off the Anchorage East of Dangar Besar, Saleh Bay (St. 315). 



3. Glycymeris lividtis (Reeve). 



1843. Pectunciilus lividiis Reeve, Proc. Zool. Soc. London, p. 190. 



1843. Pectunculiis lividus Reeve, Conch. Icon., I, PecHcnculiis, pi. IX, fig. 51. 



1845. Pectuncuhis lividus Catlow & Reeve, Conch. Nomencl., p. 52. 



1863. Pectuncuhis lividus Deshayes, Cat. Moll. Réunion, p. 22. 



1869. Pectunculus lividus Issel, Malacol. Mar. Rosso, p. 88. 



1870. Axinea livida MacAndrew, Ann. Mag. Nat. Hist., (4) VI, p. 449. 



1880. Pectuncuhis lividus von Martens, Môbius Beitràg. Meeresf. Mauritius, SeychelL, p. 320. 



1886. Axinaea livida Cooke, Ann. Mag. Nat. Hist., (5) XVIII, p. 95. 



1890. Pectunculus [Axinaea] lividus Paetel, Cat. Conch. Samm., III, p. 219. 



1901. Pectunculus lividus Sturany, Denkschr. Kais. Akad. Wiss. Wien, Math.-Nat., LXIX, p. 290. 



1906. Pectuncuhis lividus Melvill & Standen, Proc. Zool. Soc. London, p. 798. 



191 1. Pectunculus lividus Lamy, Bull. Mus. d'Hist. Nat. Paris, XVII, p. 130. 



19 12. Pectunculus livtdus Lamy, Journ. Conchyliol., LIX, p. 148. 



Of the distinguishing characters of G. lividus, as pointed out by Reeve and Lamy, the 

 angulation of the anterior side does not appear till the shell has grown to a sufificiently large 

 size, nor is the margin of the young or half grown -shells livid-blue. Young shells, such as the 

 ones collected by the "Siboga" Expédition are of a uniform reddish brown colour crossed by 

 much lighter, almost yellowish thread-like radiating lines separating the low radial ridges or rays. 



G. heroiciLs Melvill & Standen ^) from the Persian Gulf to which Lamy refers in his 

 account of this species is, as I hâve satisfied myself by an examination of the t3-pe in the 

 British Muséum (Nat. Hist.), London, quite distinct. It is distinguished by the shell being much 

 inflated, orbicular with the upper margin much less arched and angulated, much larger and more 

 excavated ligamental area, quite différent colour, and more strongly marked sculpture. 



Distribution : — G. lividus v^as originally described from the Red Sea, but has since 

 been recorded from the Island of Réunion, Mauritius and Karachi and appears to be widely 

 distributed in the Indian Océan. 



The "Siboga" Expédition dredged three valves, the largest of which is 19.6 mm. in length 

 and 18.4 mm. in height in. Wunoh Bay, N. W. coast of Waigeu Island (St. 152). 



i) Melvill, J. C. & Standen, R. — Proc. Zool. Soc. London, p. 798, pi. IV, fig. i (1906). 



