182 



THE GEOLOGIST. 



XXXIX. — PRorrcTUS spiyrLOsrs. J. Sowerbr. PI. iv., figs. 23-2i. 



Producfiis sjjiniiJo'^us. J. Sowerbv. ]\Iin. Coii., toI. i., p. 154, pi. Ixviii., fig. 3, 

 1814. De Kouiuck, Mouograpliie du Gem-e Prodiictus, pi. xi., fig. 2. 



This shell is transverselv semicirculai', the hinge-line being nearlv as long as 

 the greatest \ridrh of the shell. The ventrid valve is regidaiiy convex, and 

 evenly arclied, witliout sinus ; the beak incurved, and not overlying ihe hinge- 

 Hne, except qidte at its attenuated extremity. The eai-s are flattened, ^vitE a 

 few concentric wrinkles. The dorsal valve, which is very concave, foUows the 

 curves of the opposite one. ExterualLy the siulace is covered with numerous 

 short s:v;ne-. arranged in quincunx, and generally about half a line or so apart : 

 they oria'luaie from a smrdl slightly elongated tubercle, wliich alone is usually 

 present m the fossd. The interior arrangements are unknown, and the shell 

 does not appear to have ever at r:\ined large proportions, some Scottish 

 examples tliat have come under my observation having measured seven and a- 

 hak' lines in ieriii'tli by nine in width ; and it is always easily distinguished 

 from other Scottish species of Productus by its shape, as well as by the peculiar 

 quincunx arrangements of its slender spines. 



In Lanarkshhe P. has been collected at XeUfield and Hill Head, 



at thi-ee hundred and seveniy-iive fathoms below the Ell coal also Brock- 

 ley, near Lesmahago. In Ayrsliii-e, at TTest Broadstoue and Aucheuskeigh, 

 near Dairy. Prof. Fleming's original specimen, which is figured on om* plate, 

 was from Linlithgowshire. In Haddingtonshh-e, at Cat Craig, near Dunbar. 



XL. — PixODUcirs ^zsoLOsrs. Phillips. PL ii., fig. 21. 



Producia mesoloba. PliiUips' Geol. of Yorkslure, vol. ii., p. 215, pi. vii., figs. 

 12-13, ISoG, and De Koniuck's Mon. du Genre Productus, pi. xvii., fig. 2. 



This shell is transverse, with a very long straight hinge-line. The auriculate 

 expansions project and form attenuated cm-diual extremities, while the lateral 

 margins are rounded, and straight or undulating in front. The ventral valve 

 is very gibbous at the beak, and sometimes geuiculated towards the front, with 

 a wide flattened or slighdy concave sinus, interrupted in the middle by a 

 narrow median rib : on either side of the sinus a similar ridge or rib is present, 

 and another intervenes between these and the cardinal angles. On the five 

 ridges may be seen a few tubercles, from wliich projected small tubular spines. 

 The beak is of moderate size, and not overlying the hinge-line, except quite at 

 its attenuated extremity. The dorsal valve is concave, with a narrow median 

 groove and two slightly marked lateral ones : concentric lines of growth 

 are observable upon hotli vidves. The interior of the valves are unkno^vn ; 

 and tlie largest Scottish example that has come under my observation did not 

 exceed eight hues m length by thirteeu in width, but the shell has elsewhere 

 attained large proportions, and can always be easdy recognized on account of 

 its peculiar shape and character. 



At Braidwood, in Lanarkshire, it has been foimd at three hundred and 

 seventy-five fathom below the "• Ell coal." At Brocklev, near Lesmahago. In 

 Stirlingshire, in the Glarat lime works or Campsie main limestone. It does 

 not appear to be a very common species in Scotland. 



XLL— pEODrcxrs rusirLOsrs. Phillips. PI. iv., fig. 19. 



Prodiicta piisfnlosa. Phillip's Geol. of Yorkshire, vol. ii., pi. vii., fig. 15. lSo6. 



This sl\ell is rotundato-quadrate, rather wider than long, with a straight 

 liinge-line. somewhat shorter than the greatest width of the shell. The ventral 

 valve is gibbous, with a wide shallow mesial siuus : the beak bemg moderately 

 developed and incurved, but not overlying the hhige-line ; the am-iculate ex- 



