DECAPODA. MACRUBA NATANTIA. 531 



absent in A. provocatoris. The uropods form with the telson a powerful 

 tail fin, but the other abdominal appendages are rudimentary or absent. 

 The gills are phyllobranchiate. A zoaea form of Amphion is known, but 

 it is not certain, notwithstanding the presence of ovaries, and indications: 

 of testes in the most fully developed examples known, whether they have 

 attained the adult structure. 



Tribe 2. STENOPIDEA. 



Gills numerous and trichobranchiate. First abdominal segment not 

 overlapped by second. 1st antenna without stylocerite. Mandible 

 undivided, with a palp. First maxilliped without the characteristic lobe 

 of the Caridea. Swimmerets not coupled. 



Fam. 1. Stenopidae. Body robust, flagella of antennae long. Ant. 2 

 has a large scale. Mandibular palp 3-jointed. 3rd maxilliped pediform, 

 7-segmented, with a slender exopodite. Trunk -legs uniramous but with 

 epipodial plates, the 3 anterior pairs chelate, increasing in length and thick- 

 ness from before backwards. Branchiae trichobranchiate. 



The larva of Stenopus is hatched in the protozoaea stage and in the 

 course of the metamorphosis the 4th and 5th trunk-legs are reduced 

 (compare Sergestidae) and then grow again. Stenopus Lat., S. hispidus 

 Ind. Ocean ; Spongicola de Haan, S. venusta inhabits Euplectella and 

 other sponges. Aphareus Paulson. 



Tribe 3. CARIDEA (Eucyphidea Ortm.). 



1st antenna with stylocerite. First maxilliped with a characteristic 

 lobe on the outer border of the exopodite and terminal segments of its 

 endopodite generally expanded or distorted. Gills phyllobranchiate. 

 The first and second trunk-legs often, the others never chelate. The 

 second abdominal segment overlaps its neighbours laterally ; the endopodites 

 of the swimmerets coupled to their fellows by appendices internae. The 

 larva is usually hatched as a zoaea in which all three pairs of maxillipeds 

 are present as biramous swimming appendages (Fig. 325). A mysis stage 

 frequently follows. 



Fam. 1. Pasiphaeidae. Laterally compressed, with large abdomen; 

 rostrum small or 0. Trunk -legs with exopodites, three posterior pairs, 

 reduced. Moderate depths to deep water. Psathyrocaris W.-M. ; Pasiph- 

 aea Sav. 2nd and 3rd maxillipeds pediform. P. sivado (Riss.) British. 

 P. princeps S. I. Smith. 9 in. Atlantic. Leptochela Stimps. The genera 

 Parapasiphae S. I. Smith. Orphania Sp. B. ; and Phye W.-M. and A. are 

 deep-sea forms. 



Fam. 2. Bresiliidae. Rostrum well developed ; only the 1st and 2nd 

 trunk-legs with exopodites. Terminal segments of 2nd maxilliped not 

 expanded or distorted. Bresilia Caiman. Deep water, West of Ireland. 



Fain. 3. Acanthephyridae. Laterally compressed and dorsally car- 

 inate ; rostrum prominent, laterally compressed ; mandibular palp 

 2-3 jointed ; trunk -legs with exopodites and reduced epipodites. 

 Bentheocaris Sp. B. ; Acanthephyra A. M. Edw. from the surface to 

 3,000 faths., some phosphorescent ; Systellaspis Sp. B. ; Hoplophorus M. 

 Edw. scale of 2nd antenna large, capable of being fixed, as an offensive 

 weapon ; Notostomus A. M. Edw. ; Ephyrina Sm. (= Tropiocaris Sp. B.) ; 

 Hymenodora Sars ; Nematocarcinus A. M. Edw. with the 4 posterior trunk- 

 legs immensely elongated, deep water. 



Fam. 4. Atyidae. Mandibles without palps ; 3rd maxillipeds pediform, 



