118 F. R. C. Reed— New Crustacea, Isle of Wight. 



in the Sedgwick Museum clearly brings out. In the first place the 

 thorax of the London Clay form has its sides nearly parallel ; the 

 lateral carinas are less marked ; the cephalic part of the carapace is 

 shorter and broader ; the anterior lateral angles are produced forwards 

 into stout spinose processes ; the cervical groove is not divisible into 

 three parts, but forms a continuous gentle curve meeting the lateral 

 carinas less acutely; the hepatic depressions are deeper and larger; 

 the gastric region is lyre-shaped, and there is a prominent large 

 median tubercle just in front of it ; the abdomen is less convex and 

 the surface of the segments is much more coarsely and closely pitted, 

 and the median ridge rises into a stout tubercle ; and, finally, the 

 tubercles on the general surface of the carapace are low and rounded 

 or transverse. 



Our new species may be appropriately dedicated to the late 

 Dr. Carter. 



The Lower Senonian species known as Podocrates dulmensis (Becks 

 MS.) ' is closely related in many respects to Th. Carteri, but differs by 

 having the orbits excavated and the anterior margin of the carapace 

 toothed ; the tubercles around and in front of the gastric region are 

 differently disposed ; the lateral carinas of the thorax are not regularly 

 arched outwards ; the cervical groove is more gently and regularly 

 curved; there are fine oblique furrows on the steep sides of the 

 carapace ; the tubercles on the carinas and carapace generally are 

 rounded and not sharply pointed ; the abdomen has a median tubercle 

 and a pair of lateral ones instead of a longitudinal keel, and the rings 

 are not pitted. 



In spite of Schluter's 2 contention that Podocrates, Becks MS., 

 1850, 3 is synonymous with Thenops, Bell, 1857 (op. cit.), there seems 

 reason to doubt it, on account of the orbits in the former being 

 excavated and the anterior margin toothed, whereas in Thenops the 

 anterior edge of the carapace on each side of the rostral teeth is 

 straight, simple, and not indented or toothed. For this reason it 

 appears desirable to place our new species from Atherfield in the genus 

 Thenops, which has Th. scyllariformis as its type. 



Thenops tuberculatus, sp. nov. (PI. VII, Figs. 1, la, lb.) 

 Description. Carapace elongated, narrowing anteriorly, divided 

 transversely into two unequal parts by cervical groove ; median 

 dorsal portion of carapace flattened ; lateral portions sharply bent 

 down on each side along obscure lateral carinas curving down some- 

 what posteriorly. 



Cervical groove strong, smooth, consisting of three parts — (1) a short 

 transverse median portion about one-fourth the width of the carapace 

 at this level, and (2) a pair of lateral portions bending forward sharply 

 and running iu a slightly sigmoidal course to meet the lateral carinas 

 at about 45°, outside which they bend down and cross the sides at 

 right angles. 



Posterior end of carapace strongly concave in outline, with lateral 



1 Schliiter, Zeitschr. deut. geol. Gesell., Bel. xiv, p. 713, t. xii, figs. 1-3, 1862. 

 - Ibid., p. 710 ; id. op. cit., Bd. H, pp. 409-30, 1899. 

 ' 3 Geinitz, Die Quadersandstein, 1850, t. ii, fig. 6 (no description). 



