I04 JOURNAL OK CONCHOI.OOY, VOl,. 9, NO. 4, OCTOMER, 1898. 



l)Ut it differs from the more orl)icular P. patagonicus King, in the 

 camparativdy greater lieight of the shell, crenulatcd ribs, and un- 

 equal cars. 



Mytilus bifurcatus C>)nr.— A peculiar looking shell, about 25 

 mm. in length, strongly grooved, triangularly ovate, very gibbous, 

 and of a dark indigo blue-black colour. Reeve does not give any 

 locality, but it is recorded from California by Paetel. 



M. magellanicus Chemn. — Three young and two adult examples 

 of this fine pear-shaped shell. It is blue-black in colour, with waved 

 crenated ribs. The larger shells l)ear beautiful growths of Bryozoa, etc. 



M. ungulatus L. — With the exception of size, there seems little 

 to separate this from our My/i/us editlis. It seems to run through the 

 same gradations of form, including typical var. gallo-provincialis Lm. 

 Recorded from Chili (Cuming). Paetel makes M. ungulatus synony- 

 mous with M. latus Lm. from New Zealand, but this can scarcely 

 be correct. 



Modiolarca pusilla A. Gd. — One typical example. Recorded 

 from Kerguelen (Fischer). 



M. trapezina Lm. — Nine specimens, in various stages of growth, 

 of a very elegant shell, varying in colour from bright orange to pur- 

 plish yellow or rich sienna-brown. Recorded from Strait of Magellan 

 (Paetel) ; Kerguelen and Auckland (Fischer). 



Cyamium falklandicum sp. n. (PI. I., fig. 12). 



C. testa iiiediocri, a:quivalvi, iucequilaterali^ ohhmgo-rhonihoidali, 

 tenui, albida; valvis sub lente undique concent rice striatis, striis rudibus, 

 posticuin apud inaiginem rw^oso-la/uinatis, umbouibus promiuulis, 

 contiguis ; valvis dorsaliter post ice leniter declivibus, prolongatis, antice 

 rotundatis, ligamento corneo, exter?io, valva7n apud rectum dente car- 

 dinali viagno, bifido, apud sinistram duobus minoribus; superficic interna 

 alba, parum nitente, linea palliali indisfincta, paullum sinuosa. Alt. 7, 

 lat. 12, diam. 4 mm. 



This interesting addition to a very circumscribed genus has been 

 confused with C. antarcticum Phil., by Gwyn Jeffreys.^ This latter, 

 however, is quite distinct, and correctly-named e.xamples exist in 

 the British Museum, where also is this species without a name. 

 It is smallish in size, equivalve, very inequilateral, rhomboidal, 

 thin, white, the valves concentrically striate, and towards the pos- 

 terior margin wrinkled-laminate ; the ligament is horny and ex- 

 ternal, the posterior dorsal margin gradually sloping, prolonged, 

 anteriorly rounded, the cardinal tooth in the right valve is large and 

 bifid, in the left there are two smaller teeth ; within the surface is 



I I5rit. Conch., vol. z, p. 257. 



