.80 



4.— Tbigonia Steangei— A. Ad. 



This species is one of great rarity, and was named by Arthur Adams 

 after Mr. Fred. Strange, an enthusiastic naturalist and collector, who 

 dredged the first specimen in deep water near the entrance to Port Jack- 

 son Heads. I have not seen an example, but I gather from Mr. Angas's 

 List of New South Wales shells that it is distinguished from the other 

 species by the ribs being covered with wart-like nodules. In this respect 

 I should think it somewhat resembles T. uniophora, only that in that 

 species the tubercles or nodules occur on a portion only, and not on the 

 whole of the ribs. Mr. Angas says that a few odd valves, much worn, 

 have been washed ashore at Long Bay and Wollongong on the coast of 

 New South Wales. 



5. — Tbigonia uniophora — Gh-ay. 



The species described by Gray under the above name was obtained 

 at Cape York, the most northern extremity of the Australian continent, 

 by Mr. John Eeete Jukes, naturalist of H.M.S. Fly, during the scientific 

 voyage of that vessel between the years 1842 and 1846. It is defined by 

 Dr. Gray as a shell of a reddish-brown colour, with twenty-two or 

 twenty-three high, rather compressed, and somewhat close diverging 

 ribs. The upper part of the central, and the whole of the posterior ribs 

 are covered with close, regular, transverse plates, the lower part of the 

 central ribs with large, rounded, or oblong solid tubercles, and the hinder 

 slope with five or six nodulose ribs. To this species must be referred the 

 specimen found by me at the furthest known limit of Trigonia to the 

 westward, on the northern coast of the continent. During a very plea- 

 sant excursion from Port Darwin to Bynoe Harbour, Indian Island, and 

 the coral reefs in that locality, I found amongst a lot of rocky debris 

 and broken shells a left valve of the species under remark. It is in a 

 much worn state, but quite good enough for the purposes of identi- 

 fication. 



6. — Tbigonia acuticostata. — McCoy. 



Habitat. — South-eastern coast of Australia. I will refer to this 

 species presently. 



Up to the present time no representative of the genus has been 

 received from the western, north-western, or south-western shores of 

 Australia, but there can be little doubt that it will be taken eventually 

 when collecting and dredging are more systematically carried on in these 



