160 



GENERA OF THE SUBORDERS ORTHOIDEA AND PENTAMEROIDEA 



Costellate section 



H.ic etas 'Wilcott 1924 

 H.juba Wilcott 192+ 

 H. lesleyi Wilcoti 1908 



? H.simonW Aeon 1924 



? H. vermontana Walcott 1912 



f H.weedi^i\co\X 1924 



? Hebertella battis (Billings) 1 865 



Distinguishing characters. — Huenella is recog- 

 nized most readily by its syntrophinoid outline and 

 profile, costate or costellate exterior, pseudospon- 

 dylium, convergent brachiophore supports, and dorsal 

 musculature. 



Fig. 24. — a-c, Huenella abnormis (Walcott). a, ventral 

 internal mold, showing muscular impressions on the imprint 

 of the spondylium. b, c, dorsal internal mold and interior, 

 showing musculature and brachiophore plates {brf). ov, 

 ovarian impressions (mistaken by Walcott for muscle 

 marks); di, diductor impressions; ad, adductor impres- 

 sions; Ps, pallial sinus. 



d, e, H. texana (Walcott), ventral and dorsal exteriors, 

 showing coarse ribbing and strong fold and sulcus. 



After Walcott 1912, pi. 103. 



Discussion. — Huenella differs from Syntropkia and 

 Syntrofkina not only in the external costation but also 

 in internal characters. Internally there is a pseudo- 

 spondylium bearing the muscle impressions; at the 

 front it is elevated slightly on a prominent thickening 

 of secondary shell. From the musculature of H. ab- 

 normis the myology of this genus would appear to be 

 essentially the same as that of Syntrofhina. However, 

 the diductor and adductor scars are not flabellate im- 

 pressions outside the pallial trunks as Walcott describes 



and figures in that species (1912, p. 806, pi. 103, 

 fig. 2b). As he figures these impressions, the adductor 

 scars are posterior to the diductors; their position and 

 arrangement are accordingly unlike the ventral mus- 

 culature of any other known brachiopod. Walcott has 

 evidently mistaken impressions that are in the position 

 of, and are usually considered to be, ovarian impres- 

 sions. Furthermore, in the same figure the muscula- 

 ture is shown clearly on the floor of the pseudospon- 

 dylium and is essentially the same as that which is seen 

 commonly in Syntrofhina. 



This genus as now constituted may be divided into 

 two groups on the basis of the external ornamentation, 

 as shown above. 



H. Simon and H. weedi, according to their external 

 form and sculpture, suggest affinities with Billingsella 

 rather than with Huenella. 



Genus HUENELLINA Schuchert and Cooper 

 1931 



PL 15, figs. 14, 21, 22 



Schuchert and Cooper, Amer. Jour. Sci. (5), vol. 22, 1931, 

 p. 247. 



Genoholotype. — Huenella triflicata Walcott 

 1924, Smiths. Misc. Coll., vol. 67, no. 9, p. 526, 

 pi. 125, figs. 1-15. 



Description. Exterior. — Externally much like 

 Platystrofhia, being strongly sulcate and costate. 

 Hinge-line shorter than the greatest width of the shell, 

 and interareas well developed on both valves. Del- 

 thyrium and notothyrium open. 



Ventral interior. — Delthyrial cavity deep, teeth 

 strong and long, with well defined crural fossettes; 

 dental plates strong; pseudospondylium scarcely ele- 

 vated in front. Adductor impression subcircular, di- 

 ductor scars indefinite. Umbo-lateral spaces marked by 

 elevated subradial ridges. 



Dorsal interior. — Notothyrial cavity deep, brachio- 

 phores long, curved slightly; brachiophore supports 

 prominent, curved, and extending directly to the floor 

 of the valve; cardinal process rudimentary or absent. 

 Attached to the outside of the brachiophores and the 

 lower (anterior) side of the palintrope is a lateral 

 septum which extends obliquely toward the lateral 

 margins. 



Geologic range. — Upper Cambrian (Ozarkian) 

 of Novaya Zemlya, Arctic Russia. The only known 

 form is H. triflicata (Walcott). 



Discussion. — The main distinction between this 

 genus and Huenella is to be found in the lateral septa 

 developed under the anterior part of the dorsal palin- 

 trope. There is nothing among the Cambrian brach- 

 iopods exactly like this feature and it is diflBcult to 

 understand what purpose it could have served other 



