530 Dr. H. Woodward — On a New Foml Isopod. 





Sphceromidce. — Body short, broad, and very convex ; often con- 

 tractile into a ball; foot-jaws elongated; in some species the terminal 

 joint is not dilated at the inner apical angle, so as to become 

 palpiform ; the head is large and transverse, and in Sphceroma the 

 first segment of the thorax is laterally anteriorly produced so as to 

 reach the anterior margin of the cephalon which it embraces on 

 either side (see figure of Sphceroma serratum, Fabr. sp., Plate XV. 

 Fig. 3). The mandibles robust and angulated at the extremity, the 

 tips formed into sevaral distinct teeth, below which is a strong 

 molar tubercle. Externally, also, the mandibles are furnished with 

 a palpiform three-jointed appendage. The segments of the thorax 

 do not exhibit, when viewed dorsally, the epimera-like structure of 

 the basal joints of the legs observable in the Idoteidce. The basal 

 segments of the tail (abdomen) are more or less rudimentary, and 

 are in general soldered together, more or less completely, so as to 

 form, apparently, only a single joint, which in many species is 

 furnished with large tubercles or spines. 



Cyolosph^roma, H. Woodw., gen. nov. 

 General outline nearly circular, almost as broad as it is long. 

 Cephalon rounded and tumid in outline ; eyes moderately large, 

 cornea vitreous ; thoracic segments seven in number, broader than 

 head-shield or telson, first segment coalesced with the cephalon ; 

 segments of abdomen coalesced together, but telson apparently dis- 

 tinct. Appendages ? (imperfectly preserved). 



Cyclosph^roma trilobatum, H. Woodw., gen. et sp. nov. (PI. XV. 

 Figs, la, b, and c.) 



Description. — Outline of cephalon elliptical, twice as broad as 

 long; glabella tumid, divided by strongly-marked furrows into three 

 well-defined regions, a central, and two lateral parts ; the central 

 portion of the glabella is broadest in front, much constricted near 

 the centre, expanding again into a small pentagonal area behind, 

 where it unites with the first thoracic somite. 



The two lateral lobes are ovate-oblong in form, broader in front, 

 and narrower behind, where they abut against the constricted centre 

 of the median lobe. The eyes, which are reniform in outline, and 

 measure 5 mm. in length by 2-| mm. in breadth, occupy the outer 

 posterior angles of the two lateral lobes ; the coi'nea is smooth and 

 glassy, but exhibits distinct facets within (when viewed under a good 

 platyscopic lens). A narrow ridge separated by a double furrow 

 marks the line of division between the cephalon and the first thoracic 

 segment, which in the living Sphceroma usually encloses the posterior 

 and lateral margins of the cephalon, with which it is more or less 

 completely united. 1 



1 In the majority of the Isopoda the "head" segments become fused with the 

 first segment of the thorax, and form a cephalic shield which is freely movable upon 

 the second thoracic segment. In Serolis the first and second thoracic segments are 

 closely united, and completely fused dorsally, though the sterna of the two remain 

 distinct ; in some species an incomplete transverse suture upon the first epimera 

 seems to mark the line of division between the two segments dorsally ; in others the 



