654 CLASS X. 
Crossurus RaruKker. (Not different perhaps from genus Tunais). 
Note-—Add genus Rhaa Epw. (Ann. des Sc. Nat. xu. 1828, 
pp. 292—296, Pl. 13 a), unless it be better to refer it to the 
Amphipoda. Genera Hupheus and Olisca Risso, seem to be un- 
certain, and require confirmation by more diligent observation. 
Perhaps also will have to be placed here amongst the Isopoda, Oniscus 
arenarius SLABBER Natwurk, Verlust. Tab. x1. fig. 4, genus Pterygocera 
Latr., Cuv. R. Ant. and éd. 1829, Iv. p. 124. 
Family XX. Idoteidea. Tail mostly composed of only three 
distinct segments, with last segment large, scutiform. Abdominal 
feet branchial; last pair of feet forming opercular lamin covering 
the branchiz beneath. No appendages exsert in the last segment 
or at the sides of tail. Antenne four, very frequently unequal, the 
middle approximate. Mandibles destitute of palps. 
Anthura Leacn. Four antenne, short, subulate. Body slen- 
der, vermiform. Anterior feet incrassated, terminated by an in- 
curved hook. Tail with two distinct segments. 
Sp. Anthura gracilis LEACH, Oniscus gracilis Montacu, DesmaRr. Crust. Pl. 
46, fig. 13, MitNE Epwarps Hist. nat. des Crust. Pl. 31, figs. 3—5. 
Idotea FAsr. Middle antenne short, with four joints, the last 
elongate, cylindrical; external antenne large, with first five joints 
thicker, the rest more slender, running into a terminal seta. All 
the feet of trunk terminated by an incurved claw; those of the first, 
second and third pairs raptorial, incrassated at the apex and turned 
forwards. Branchial feet of tail covered by the last pair of feet 
changed into two valves articulated by means of a hinge to the 
last segment. 
Sp. Jdotea entomon Fasr., Oniscus entomon L. (in part), Patuas Spicil. 
Zool, 1X. Tab. Vv. figs. 1—6, Du GuEer Mém. p. s. a U Hist. des Ins. vi. Pl. 
32, figs. I—10, RatHKE Beitr. zur Gesch. der Thierwelt, 1. Danzig, 1820, 
Tab. Iv. This animal was found in the Baltic Sea; it attains a length of 
19”. Its two small black eyes are situated at the side of the head in a 
round pit, and are not, as is erroneously supposed, simple, but each of them 
consists of a group of more than 50 small oval eyes placed close together.— 
Idotea Lichtensteiniti Krauss, Siidafrik. Orustaceen, Stuttgart, 1843, Tab. 
Iv. fig. 4. 
Idotea linearis Latr., Stenosoma lineare LuAcH, BasteR Natuurk. Vitsp. 
i. Tab. xii. fig. 2, Desmar. Crust. Pl. 46, fig. 12; from the Baltic, about 
1” long. 
