154 



BRITISH FOSSIL CRUSTACEA. 



I include under this species the fragments of body-joints drawn on pi. x, ' Mem. 

 Geol. Surv.,' Mon. I, the more or less fragmentary remains of six endognathary palpi 

 and three swimming-feet or ectognaths drawn on pi. xi (op. cit.) [the most perfect of 

 these last-named organs is reproduced on PI. XXIX, fig. 2] ; also the remains on pi. xiii 

 (op. cit) attributed to Pterygotus (now Eurypterus) punctatus by Mr. Salter. 



I would, however, venture to exclude : — Firstly, the remains of the chelate antenna^ 

 — my reasons for so doing being that all the species of Merostomata with spinose palpi 

 have small, simple antennules {e.g. Eurypterus, Stylonurus, Slimonia). 



Secondly, the lip-plate. 2 The form of the lip-plate is very characteristic of the separate 

 divisions of this genus ; and I am not aware of any other species which possesses such a 



metastoma as is found in E. scorpioides, and which, from the 

 a detached plate now figured (see Woodcut, Fig. 50, p. 155), I 



doubt not, also marked E. punctatus, the Leintwardine species. 

 I would therefore suggest that the detached lip-plate (' Mem. 

 Geol. Surv.,' Mon. I, pi. xi, fig. 4) must have belonged to some 

 species of another genus — the form of the plate being nearer 

 that of Slimonia acuminata. 



Thirdly, the telson. Mr. Salter observes that "it is yet 

 wanting," and that " in all probability it was not unlike that 

 figured on pi. x, fig. 11, which has possibly something to do 

 with it." On the fragment referred to I Avill not venture to 

 give an opinion, but will only observe that, as far as I can 

 ascertain by a careful comparison, such a form as E. punctatus 

 would have had an ensiform telson, as in the other Eurypteri, 

 with which I venture to place it. 



The characters by which the fragmentary remains associated 

 together under this name have been distinguished are — the 

 form of the joints of the palpi, with their pairs of long, slender, 

 recurved spines, and their well-marked basal joints {coxognathites) ; 

 the form of the great swimming-feet (see PI. XXIX, fig. 2), 

 expanded in the penultimate joint, and attenuated at their ex- 

 tremities ; the peculiar shield-shaped metastoma or post-oral plate 

 (Woodcut, Fig. 50) ; and, lastly, the distinct punctate ornamen- 

 tation which characterises the surface of the body-segments and 

 appendages. 

 Mr. Salter writes (op. cit., p. 99), " Of the carapace or eyes we have yet no trace. 

 But the epistoma presents us with a singularly neat character for the species." This 



Fig. 49. — Median appendage of 

 the thoracic plate, or oper- 

 culum,of Eurypterus puncta- 

 tus. a would be the centre of 

 the attached border; i, i, the 

 position of the intercalated 

 triangular plates uniting the 

 median appendage with /, /, 

 the two lateral ate of the 

 operculum ; f, the free ex- 

 tremity of the median ap- 

 pendage. 



1 PI. xi, figs. 1, 2, 3, 'Mem. Geol. Surv.,' Mon. I. 



2 PI. xi, fig. 4, op. cit. 



