81 



10. Argiope Neapolitana, Scacchi, sp. (PI. XIV. fig. 24, 25.) 



Terebratula Neapolitana, Scacchi, Oss. Zool. ii. p. 18. 



Terebratula seminulum, Philippi, En. Moll. Sicilise, 1836 ; Sow. 

 Th. Conch, pi. 71. f. 85, 88. 



Argiope Forbesii, Dav. x\nu. and Mag. of Nat. Hist. May 1852. 



Diagnosis. — Shell small, suborbicular, nearly as long as wide, com- 

 pressed, emarginated in front ; valves unequal, slightly convex, almost 

 smooth or ornamented by a few rounded and nearly obsolete radiating 

 costse ; a longitudinal depression extending along the centre of the 

 smaller valve ; beak produced ; foramen large, with a small, lateral, 

 deltidial plate, and an area on either side ; hinge-hne straight ; 

 apophysary system consisting of a small longitudinal mesial septum, 

 with a complete two-lobed loop ; colour light yellow ; structure 

 largely punctate. Length 1^, width 1^, depth \ line. 



Hab. Naples, and different parts of the Mediterranean, in from 

 60 to 105 fathoms (Forbes). 



Obs. — Since the pubUcation of my paper in the 'Annals,' May 

 1852, I have, through the kindness of Mr. Hanley, been enabled to 

 examine two specimens, said to be the types of Scacchi' s Ter. Nea- 

 politana, and, according to Kuster, the Ter. seminulum of Philippi 

 would be a synonym ; although the last-named author's species, 

 from his illustration presenting a deep notch in the umbo (a character 

 never seen in any Argiope), had led me erroneously to believe T. se- 

 minulum the same as Prof. Forbes's T. appressa. The figures of 

 Ter. Neapolitana given both by Scacchi, Philippi, and Kiister, do 

 not represent the characters of the species under notice, — so much 

 so that I believed it new, and gave to it the name oi Argiope Forbesii, 

 which must now be considered only a synonym : and Sowerby's 

 figure correctly illustrates the species. In my plate I have also added 

 a figure of the apophysary system of A. decollata, Chem. (fig. 26), 

 and that of T. Neapolitana (fig. 25), to show the difference in the 

 lobes of the loop in these two species ; the arms in the first being 

 four-lobed, whilst in the other recent forms, such as Argiope Neapo- 

 litana (fig. 25), A. cistellula (fig. 28), and^. cuneata (fig. 27), there 

 exist only two lobes to the arms. 



11. Rhynchonella nigricans. Sow. sp. 1846. (PI. XIV. 

 fig. 30,31.) 



Diagnosis. — Shell inequivalve, irregularly tetrahedral, wider than 

 long ; beak acute, and slightly recurved ; foramen not entirely sur- 

 rounded by the deltidial plates, a portion being completed by the 

 umbo ; beak-ridges well defined, leaving between them and the hinge- 

 line a false area, not indenting much the smaller valve ; surface orna- 

 mented by a variable number of sharp plaits, about twentj'-five' on 

 each valve, a few of which are due to intercalation ; mesial fold not 

 prominent, but defined, with a corresponding shallow sinus in the 

 larger valve ; apophysary system consisting of two short curved 

 lamellae ; colour bluish black ; structure impunctate. Length 8, 

 vddth 9, depth 4 lines. 



No. CCXLIII. Proceedings of the Zoological Society. 



