ordovician brachiopoda 113 



Table 82 



Statistics of length (1) and length of ventral muscle scar (sc) in n pedicle valves of Tissintia 



prototypa (Williams) from the Weston Beds (A) and the Lower Llanvirn of Llandeilo (B), and of 



T. immatura (Williams) from the Meadowtown Beds (C) 



ABC 



n 20 17 43 



lmm(varl) 11-45 (9-581) 9-51(2-327) 7-5(13-902) 



sc mm (var sc) 4-11 (i-88i) 3-31 (0-432) 2-84 (2-991) 



r 0-934 0-729 0-96 



log e l (var log e l) 2-4023(0-0706) 2-2392(0-0255) 1-9048(0-2208) 



logesc (var log e sc) 1-3606(0-1056) 1-1762(0-0389) 0-8848(0-316) 



r e 0-937 0-73 0-967 



a (var a) 1-2231(0-01008) 1-2351(0-04747) 1-1963(0-00229) 



Table 83 



Statistics of length (1) and maximum lateral extension (w) of the brachiophore bases of n brachial 

 valves of Tissintia prototypa (Williams) from the Lower Llanvirn of Llandeilo (A) and T. imma- 

 tura (Williams) from the Meadowtown Beds (B) 



A B 



n 61 67 



1 mm (var 1) 1-22 (0-069) I-0 9 (0-382) 



w mm (var w) i-i (0-065) I-2 9 (0-44 1 ) 



r 0-895 0-927 



logel ( var logel) 0-1729(0-0457) -0-0527(0-2783) 



logew (var logew) 0-0707 (0-052) 0-1372 (0-235) 



r e 0-9 0-935 



a (var a) 1-0674 (0-00367) 0-919 (0-00163) 



Table 84 



Proportions of the earlier insertion of 10 costellae relative to 10 others (with the number of bra- 

 chial valves in which both costellae originated at the same growth stage in brackets) for Tissintia 

 prototypa (Williams) from the Weston Beds (A) and the lower Llanvirn of Llandeilo (B) and for 

 Tissintia immatura (Williams) from the Meadowtown Beds (C) 





A 



B 



C 



lal ) IB 



i/7 (1) 



0/6 (2) 



i/4 (2) 



IB ) la° 



8/8 



10/13 (1) 



5/9 (1) 



2B ) 2a 



9/9 



15/17 (1) 



11/12 (2) 



2C ) 2a° 



i/3 



2/" (3) 



0/4 (1) 



2a.l ) 2B 



i/3 (5) 



o/5 (7) 



2/8 (3) 



3ala ) 3a 



i/4 (4) 



0/14 



3/14 (1) 



3£ ) 3a 



2/7 (2) 



0/15 



1/12 (1) 



3ala ) 2a 



8/8 



3/10 (2) 



9/12 



46 ) 4 b° 



8/8 



3/3 (2) 



i/4 (3) 



4&P ) 4BI 0/2 1/3 2/3 



