EEPORT ON THE AMPHIPODA. 463 



pyramidal oliez les Cijpridina e.t Lijsianassa; claviforme chez les Isaa ; cylindro-conique 

 daus certains Squilla, etc." 



1877. HOEK, P. P. C. 



Carcinologische Aanteekeningen. Bijdrage tot cle Kennis der Noordzee-Fauna 

 (2de Jaarslag, 1877). 



No new Amphipoda are reported. 



1877. Huxley, Thomas Henry. 



A Manual of the Anatomy of Invertebratcd Animals. London, 1877. 



The Edriophthalmia are described on pages 359 to 367. " These resemble the Podopldhahnia 

 in never possessing a greater than the typical number (20) of somites, though, in some 

 members of the group, the body is composed of fewer somites, in consequence of the abortive 

 or rudimentary condition of the abdomen." The genus Amphitlwe is chosen for special 

 description, but it is not easy to see why this name should have been chosen for the 

 animal figured, which has a large rostrum, the back carinate and almost every segment 

 dentate, the fifth side-plate shorter than the fourth, and the upper antenna showing a 

 secondary flagellum, suggesting, therefore, Gammaracanthus loricatus rather than any 

 AmpJnthoe. The head proper, in Professor Huxley's view, has only five pairs of appendages, 

 the sessile eyes not being counted. These are the antennules, antennas, mandibles, and two 

 pairs of raaxillfe. The first pair of thoracic api^endages " are applied against the mouth, 

 and form a large lower lip." "The ' head ' of AmpMfhoe, therefore, is formed by the 

 coalescence of the seven anterior somites of the body ; but I believe that the tergum of the 

 seventh (or first thoracic) somite is obsolete, as in a Stomatopod, and hence that the tergal 

 surface of the head of the Edriophthalmia corresponds exactly with the cephalostegite (or 

 that j)art of the carapace which lies in front of the cervical groove) in Podopjldhalmia. 

 Mr. Spence Bate has shown in his valuable ' Report on the Edriophthalmia,' that, in the 

 Crustacea at present under discussion, a strong apodeme arises on each side from the 

 posterior part of the sternal region of the head, and passing inwards and forwards meets 

 with its fellow, to form an endophragmal arch, which supports the oesophagus and stomach 

 and protects the nervous commissure between the first and second sub-oesophageal ganglia, 

 which runs under it. The discoverer of this structure conceives that it represents the terga 

 of the three somites immediately succeeding the mouth ; but I cannot see that it is other 

 than the representative of the precisely similar niesophragm formed by the anterior apodemes 

 in Astacus. In fact, the correspondence in structure between the head of an Amphitho'r 

 and the cephalic portion of the cephalo-thorax of Astacus is not a little striking. There is 

 the same sternal flexure, the same relative position of the stomach, and of the insertions of 

 the mandibular muscles. The great difference lies in the abortive condition of the 

 ophthalmic appendages." In treating of the embryology the remark is made that " in 

 certain Amphipods (Gammarus locusta and Desmophilus) the viteUus undergoes complete 

 division ; while, in closely allied forms {Gammanis fluviutilis and pule.r), and stUl more 

 completely in those Isopoda which have been studied, the part of the vitellus which divides 

 into blastomeres, becomes more or less completely separated from the rest immediately after 

 fecundation, and the so-called partial yolk division, take place." A note gives a reference 

 to "E. van Beneden, Eecherches sur la Composition et la Signification de I'CEuf, 1870." 

 By consulting this work Mr. W. E. Hoyle has found for me the clue to the mysterious 



