290 PROCEEDIJS^GS OF THE GEOLOGICAL SOCIETY. [Maich 25, 



ill breadth, having one entire swimming-foot and three pairs of palpi 

 ill situ, and presenting the dorsal aspect of the body to view. 



(2) I met mth a second example of this species in the Museum of 

 Practical Geology, Jermyn Street (see PL X. fig. 2). It consists of 

 the anterior part of an individual about the same size as that first 

 mentioned, exhibiting, in situ, the ventral aspect with the postoral 

 plate or metastoma (?n), the bases of the swimming-feet {e, e), three 

 pairs of perfect palpi (6, b), and the basal joints of what may perhaps 

 prove to be two anterior organs corresponding, in position, to the 

 antennae (a, a). 



(3) I consider the detached organs and fragmentary remains 

 figured on plates x., xi., and xiii. of Monograph I. of the Memoirs 

 of the Geological Survey to be, in great part, referable to a species 

 very closely allied to that from Logan Water. 



(4) I am enabled to figure a very fine lip-plate, obligingly left for 

 my examination some time since by Mr. J. W. Salter, E.G.S., which, 

 like the remains figured in the Survey Monograph, was obtained 

 from the Lower Ludlow rock, Leintwardine, Shropshire (see PI. IX. 

 fig. 2). 



II. The second new form is represented (PI. X. fig. 1) by the im- 

 pression and counterpart of an entire specimen, measuring 2 inches 

 in length and 1 inch in breadth, having all its appendages in situ. 



That this may possibly be the young of some larger species I do 

 not deny ; but being quite distinct in general character from every 

 form hitherto met with, I think it deserving description. 



III. The third new species (PI. IX. fig, 3) is at present known only 

 by a single example, consisting of a head-shield and six mutilated 

 segments. 



The head is remarkable for its obtusely pointed triangular shape 

 and prominent marginal eyes. It approaches somewhat in form to 

 Pterygotus BanTcsii from the Lower Ludlow rock, but it cannot be 

 referred to that species. 



1. Etjrypteeus (Pteetgotus) puis^cTATus, Salter, sp. 



[Geol. Surv. Mon. I. 1859, p. 99, pi. x., pi. xi. figs. 5, 6, 7, 8, 9, 

 12, 13, 14 & 15, pi. xiii. figs. 5, 6, 9, 10, 11, 14.] 



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 (coccognathites) ; the form 

 of the great swimming-feet, expanded in the penultimate joint, and 

 attenuated at their extremities ; the peculiar shield-shaped meta- 

 stoma or postoral plate ; and, lastly, the distinct punctate ornamen- 

 tation which characterizes the surface of the body-segments and 

 appendages. 



]^Ir. Salter has attributed to this species a pair of long, slender, 

 chelate antennae ; but I have no evidence in confirmation of this 

 point, and, as these remains occur in the Lower Ludlow rock as 

 detached fragments, their association with this species is, I venture 

 to think, merely hypothetical. 



