PHYSOCARIS VESICA. 67 



1885. Phxsocakis vesica, T. B. J. & S. W. Third Report Pal. Phyll., p. 353 ; 



Geol. Mag., 1885, p. 467. 



1886. — — — Fourth Report, p. 233 ; Geol. Mag., 



1886, p. 460. 



Of this curious fossil Phyllopod, having a small bladder-like carapace, described 

 by Mr. Salter in 1860, only one specimen is known. It is in Mr. Theodore Salwey's 

 collection at Ludlow. It differs slightly from Mr. Salter's woodcut figure, being 

 larger, and showing an appearance of having been broken away to a little extent 

 near one end so as to leave a broad notch at the slope behind an angle, and these 

 together constitute the prominence in Mr. Salter's woodcut figure. If continued 

 over this notch, the outline of the shell would be nearly that of a broad oval, 

 whereas now it is broadly and obliquely pyriform (25 X 18 mm). 



This specimen of Physocaris vesica, Salter, we consider as having had its 

 abdominal segments shifted further upwards, and turned over on their axis, after 

 death ; and therefore as having been figured both by Mr. Salter, and in PL VII, 

 fig. 8, upside down. The annexed woodcut shows what we consider to have been 

 the natural position of the carapace and abdomen. 



The relative position of the animal in these Phyllopods is indicated by the 

 telson occupying the upper part of the caudal appendages attached to the abdomen. 

 In this instance, however, the abdomen 1 has been twisted about, so as to be in a 

 reversed position. There are seven exposed segments of the abdomen, which 

 appears to come out from the lower and hinder quarter of the carapace but really 

 (being inverted) from the upper postero-dorsal edge. From the imperfect preser- 

 vation of some of the segments, the abdomen (16 mm. long) seems to be very 

 slender near its origin, but higher at its ultimate segment (which is 7 mm. long). 

 The proximal abdominal segments are only partly exposed ; hence their narrowness 

 is accidental and not a feature. The telson is 11 mm. long. One lateral spine 

 (stylet), 7 mm., is present. The whole animal had a length of about two inches. 



It was collected by the late Mr. Salwey in the Lower Ludlow at Leintwardine ; 

 and Mr. Salter at first labelled it as Ceratiocaris infiatus. 



Fig. 3. — The probably true position of the carapace and abdomen in Physocaris vesica. 



PI. VII, figs. 8 a, 8 b. Carapace figured upside down; in olive-grey, micaceous 

 sandstone, not calcareous ; with scattered casts of small Brachiopods and Bivalves, 

 as well as Polyzoa, Beyrichia Kloedeni, and other little fossils on a plane of 

 The abdomen in PI. XII, fig. 1, is also not only shifted but upside down. 



