428 Dr. H. J. Hansen on the Morphology of the 



maxillce of authors) in the Malacostraca, and the labium as 

 homologous with the maxillijjedes and agreeing in many 

 resvects icith these appendages in the case of the group men- 

 tioned. The submentum is homologous with the first segment, 

 ■which is fused in the Gammarina, and the mentum with the 

 second segment, which in the Hyperinas is likewise fused. 

 At the tip of the mentum we find a segment, ])roduced on 

 each side into four lobes, which, as may be seen witli sufficient 

 clearness, belong to two lobes, eacii of which is cleft ; and 

 these I regard (among other reasons on account of a compa- 

 rison with Orthoptera and Amphipoda, although I cannot 

 bring forward any cogent proof derived from the skeletal 

 parts) respectively as a lobe from the second segment (the 

 innermost cleft lobe) and as the third segment of the labium 

 with its cleft lobe : the palpus arises from the outer side of 

 the third segment. 



32. The hypopharynx is conspicuous, almost rectangular 

 in shape, slightly emarginate in front, and homologous with 

 the hypopharynx (paragnathi) in the Malacostraca. The 

 organs which are termed " paraglossse " by authors have 

 nothing to do with the hypopharynx ; in the skeleton of the 

 head they are articulated at the bottom of the hypopharynx 

 and have a somewhat complex structure, with an external 

 process like a small single-jointed palpus, and towards the tip 

 a distinct tendency to cleavage into two lobes. I regard 

 these ''' paraglossffi " as homologous with the maxillulge of 

 Crustaceans (a supposition which is strengthened in the 

 highest degree by their structure in Japyx and the Collera- 

 bola, vide § 39) ; the essential difference in Machilis consists 

 in the fact that they are situated somewhat nearer to the 

 median line and lie partly in front of the hypopharynx ; yet 

 in Argulus, according to Glaus, the maxillge are enclosed 

 together with the mandibles in the suctorial tube, and are 

 consequently placed before the hypopharynx. (If a carcino- 

 logist should raise the objection tliat in the case of Apseudts 

 we find a lobe resembling an appendage upon the hypopharynx, 

 we must reply that in Apjseudes only the elongated outermost 

 anterior angles are segmented off in a secondary fashion, 

 while in Machilis, Japyx, and the Gollembola the maxillulaj 

 arise from the skeleton of the head at the base of the hypo- 

 pharynx, which in these animals is not cleft towards the tip.) 



33. Tlie thoracic appendages have an elongated coxa, 

 which is attached to the body by means of a small and for 

 the most part firmly chitinized segment, which is freely 

 movable, and which on account of its position and shape we 

 must regard as the first joint of the leg. I regard it as homo- 



