Dr. F. A. Bathe') — Eocystis. 55 



animal that owned the stellate plates. Their association in the rock 

 suggests that they did so, but the relatively small size of so many 

 suggests that they did not. 



On specimen G. F. M. (?, a worm-like body, about 11 mm. long and 

 1-25 mm. wide, and marked with obscure transverse striae, is labelled 

 by Dr. Matthew '■'■ Eocystites frim(Bva, stem!" One end lies against 

 a stellate plate, but there seems no other reason for this ascription. 



4. The Undetermined Plates include many obscure impressions and 

 patches of various sizes and shapes — or rather absence of definite 

 shape. There seems no reason why some of them should not belong 

 to Eocystis, nor any why they should. There are several examples 

 of a trihedral sub-pyramidal impression, probably produced by the 

 angle of a plate. The wax squeeze drawn (Fig. 19) is taken from 

 the largest of these (/c). Another type is represented by j, the 

 squeeze of which (Fig. 18) shows curved sides meeting in a rounded 

 ridge with a wide angle and a rather sharp edge or lip in front. 

 Other forms are shown in h and h! (Figs. 16, 20), but without figuring 

 every specimen one cannot convey an idea of the variations in shape 

 of these rounded surfaces. Among the fragments is an apparent 

 spine, I, possibly the infilling of a coluranal (Fig. 17). There are 

 also some minute rounded impressions, which may represent the 

 intercalary plates of Eocystis. 



From the various plates and ossicles now described it is not easy to 

 reconstruct the form of Eocystis. We can recognize the stellate 

 plates of the theca and the biconcave columnals, and we are led 

 by their numbers and their association to suppose that both belonged 

 to the same form. If this be so, then Eocystis possessed a flexibly- 

 walled iheca borne on a slender flexible stem. One can detect no 

 obvious brachiolars, and the undetermined ossicles seem too large to 

 be thus interpreted. Possibly they represent proximal columnals 

 such as occur in the Heterostelea, to which group Trochocystis 

 belongs. Comparison may profitably be made with the stem of 

 Cothurnocystis (Bather, 1913, " Caradocian Cystidea from Girvan," 

 Trans. Ptov. Soc. Edinburgh, xlix, pt. ii, No. 6, §§ 200-6, 

 text-figs. 19-23). 



If Eocystis be rightly referred to the Heterostelea, it by no means 

 follows that it belongs to the Trochocystitlse. The stellate plates are 

 unlike the close-fitting hexagonal plates of Trochocystis (Barrande, 

 1887, Syst. Sil., Cystidecs, pis. iii, iv), and there is no trace of the 

 characteristic marginals. For similar reasons Eocystis cannot be 

 referred to the Cothurnocystidse or Ceratocystidae, and still less to 

 the Anomalocystidae. It may have resembled Bendrocystis in the 

 irregular arrangement of its thecal plates, but it diifered in the 

 cylindrical or dice-box columnals. 



For the interpretation of Eocystis it will therefore be necessary to 

 consider other forms than Eocystis primcBva, both such forms as may 

 have been referred, with or without hesitation, to Eocystis, and such 

 obscure remains as may have received yet other names. That inquiry 

 may form the subject of a future article. 



