202 THE VOYAGE OF H.M.S. CHALLENGER. 



of side-plates (eijimera) only carries a little further the reduction observed in some 

 Amphipoda, especially Gammarina gressoria. Where the action of the pleon keeps up a 

 fresh supply of water to the branchiae, Kr0yer thinks that the side-plates covering the 

 branchiae may attain theu- fullest development without interfering with respiration, but 

 that in the Laemodipoda, there being no pleon to fulfil this oflice, the branchiae have to be 

 left free. The absence of a pleon he connects with their mode of life, which leads them 

 to cling and climb, and only very rarely to swim. Important as this mark of difference 

 is, Kr0yer urges that its weight is much diminished by the discovery of two new genera 

 of Lsemodipoda, in one of which the pleon, though small, has five segments, in the other 

 • only two, but in both is furnished with two pairs of jointed limbs. Thus, he considers, a 

 transition is established to those Amphipoda, such as CorojjJiium, in which the pleon 

 is less strongly developed. He mentions that the genus Cerapodina wants feet on some 

 of the segments of the peraeon in common with the Laemodipoda, but that argument only 

 rests on the faulty description of Cerapodina. He considers that the Laemodipoda, as a 

 family or division of the Amphipoda, come nearest the Gammarina greasoria, referring to 

 the pediform antennae among other marks of resemblance. He characterizes the family 

 as follows: — "Pleon rudimentary or only little developed. Xo Epimera. The Krst of 

 the seven peraeon-segments united with the head along an oblique line, its pair of feet 

 projecting under the maxiUipeds. Feet generally wanting on the third and fourth 

 peraeon-segments. All the feet are in general claspers, that is to say, furnished with hand 

 and movable finger. Only two or three pairs of branchial vesicles (on the second and 

 third [3rd and 4th], or on the second, third and fourth peraeon-segments). Antennae 

 more or less pediform, the upper always larger and stronger than the lower. Eyes very 

 small, circular." Of the famUy he makes two subdivisions : — " Cajjrellina. Form generally 

 very elongate, thin, cylindrical. Branchial-plates bladder-like. The lower antennae of 

 moderate size, and the feet of moderate strength. Often a palp on the mandibles. 

 " Cyainea. Form generally very flat and broad. Branchial-plates very large, sword- or sabre- 

 .shaped, sometimes bipartite, in the males furnished with special appendages at the base. The 

 lower antennae rudimentary. Feet extraordinarily developed. Mandibles without palp." 



The general form, he says, has ceased to be a striking distinction between the two subdivisions, 

 since the discovery of a thin Cyamus in Cyamus grarilis, and a stout Caprella in CapreUa 

 dilatata. To the CapreJlina he assigns four genera, L Leptomera, Latr., 2. Cercops, Kr., 

 3. JEgina, Kr., 4. Caprella, Lam. All these he defines ; the two new ones as follows : — 

 Cercops. " Quinqve pedum paria, omnia manu armata subcheliformi. Mandibula palpo 

 iustructa triartioulato. Flagellum antennarum inferiorum biarticulatum, articulo ultimo 

 primum ferme longitudine aequante. Tria vesicularum branchialium paria (aunuli thoracici 

 secundi, tertii & quarti). Abdomen distinctura, qvinqvearticulatum, appendicibus quatuor 

 elongatis, biarticulatis." .JSgina. " Qvinqve pedum paria, omnia manu armata subcheli- 

 formi. Mandibula palpo instructa triarticulato. Flagellum antennarum inferiorum 

 biarticulatum, articulo ultimo fere rudimentari. Duo vesicularum branchialium paria 

 (annuli thoracici tertii et quarti). Abdomen minutissimum, sed sat distinctum, biarticulatum, 

 appendicibus qvatuor elongatis, duabus anterioribus biarticulatis, posterioribus uniarti- 

 culatis." 



Latreille's Naupredia {Naupridia in Milne-Edwards) is dismissed by Kr0yer as founded on 

 a misconception, and the identity of Profo, Leach, with Leptomera, Latreille, being pointed 

 out, the claim of Profo to priority is vindicated. Why Krpyer himself does not adopt it is 

 not explained. 



" Caprella Januarii Kr. (Tab. VI. fig. 14-20)" from Eio-Janeiro, is described with much 

 detail. This species is identified by Spence Bate with the earlier Caprella xquilihra, Say. 

 Mayer agrees with Spence Bate, and points out that KrOyer, usually so exact, does 



