210 DE. C. CHILTON ON THE SUBTEREANEAN 



Avith Norman and Stebbing's descriptions; but even this must be considered merely 

 provisional, as only the one species is known, and nothing is known of tlie distinctive 

 characters of the tw^o sexes : — 



Eyes wanting. Segments of the jileon separate (in both sexes ?). Both pairs of 

 antennoe Avithout distinct flagella (in adults ?). Mandibles without palp. Maxillipedes 

 not divided into separate joints. Last segment of the perseon small and without 

 ajipendages (in adults ?). 



All the specimens that I have seen, many scores in number, agree in having the 

 seventh segment of the 2iera3on small and without apjiendages ; but as I have never seen 

 a specimen that I could be certain was sexually mature, I am doubtful whether this 

 character would hold in the adult also or not. My specimens have been obtained from 

 several wells in different localities, and were collected at different times during a period 

 of about ten years, and it seems scarcely likely that all the specimens should be immature, 

 and that during the whole time not a single mature sjiecimen should be obtained, unless, 

 indeed, the adult differs from the immature form in habits in such a way as to prevent it 

 being liable to be drawn up by the pump. I have one specimen that has the integument 

 of the under surface of the perseon much expanded, somewhat in the same way as shown 

 by Stebbing in his figure of the " gravid female " of Faranthura nigro-punctata [106, 

 pi. xxvi. fig. ii. D, ? ] ; but in my specimen I can discover no trace of eggs or young, and 

 it appears to be the integument itself that is distended, and not a pouch formed by 

 brood-plates attached to the bases of the legs in the usual way ; so that I am uncertain 

 whether this specimen is really an adult female or is abnormal in some way, o\v^ing 

 perhaps to half-completed ecdysis or some similar cause. 



All this uncertainty makes comparison of Cruregens with other genera of the 

 Anthuridse a very difficult task, but it aj^peavs to approach to Taranthura more nearly 

 than to any other. It resembles this genus generally in the antennoe (leaving out of 

 consideration the special brush-like antenna of the adult male in Parcmthiira), in the 

 perseon and its appendages, and in the pleon and the pleopoda, though the uropoda are 

 much more slender in Crnregeiis. It differs, however, in the mouth-parts, for the 

 mandibles have no palp and the maxillipedes have lost all trace of sejiarate joints. If 

 the absence of tlie seventh pair of legs is a character that holds in adults, this would 

 form another difference between the two genera. 



It is to be noted that the seventh pair of legs appears to be developed at a later period 

 of the life-history in the Antliuridre than in other Isopoda, for sjiecimens without them, 

 but ap2)arently mature in other respects, are not infrequently met with. Besides 

 Ci'uregens w^e have the following examples : — Hyssura ■])roducta is founded on a single 

 specimen about a quarter of an inch long, of which Stebbing and Norman say " the last 

 segment of the person in the type specimen has no legs, nor can we see any sign of scars 

 where they would have been attached, and the specimen was otherwise quite perfect " 

 [106, p. 128] ; Faranthura neglecta, Beddard, is said to have the seventh segment of the 

 perfEou absent, the specimen is 6 millim. long, and from the absence of the last pair of 

 legs Beddard considers it to be immature, though he does not mention any other point of 

 immaturity about it [9, p. Ill] ; I have also a small specimen of an Anthurid from Port 



