Limbs and Mouth-parts of Crustaceans and Insects. 431 



higher Collembola the hjpopharjnx is of large size and tlie 

 maxillulffi have only an inner and an outer lobe (" para- 

 glossse " and palpus). Stumnier-Traunfels furnishes us 

 with a good rSsumS of the extremely divergent interpretations 

 of these parts by different authors, such as Meinert, Lubbock 

 (who terms the " paraglossje " the " second maxilla "), and 

 TuUberg (whose description is on the whole excellent and 

 who possessed a keen eye for the difficulties in the interpre- 

 tations given by the two previous writers). The raaxillulje 

 are, as has been already stated, inserted before the maxillje 

 and behind the point of origin of the hypopharynx ; they have 

 notliing to do with the labium. 



40. It appears to me that the facts detailed in §§ 28-32 and 

 36-39, when taken together, show the great agreement that 

 exists between the mouth-parts of the primitive Insects named 

 and those of the Malacostracous Crustacea and that tliey 

 render evident the homologies which I have set up. 



41. Lepisma stands, as regards the structure of the mouth- 

 parts and the thoracic feet, between Machilis and the Ortho- 

 ptera. 



42. Hemimerus taJpoides^ Walk. *, is a genuine Ortho- 

 pteron, and in the structure of its mouth-parts approaches 

 very near to Forjicula. 



43. Orthoptera. — The muscles of the mandibles, e. cj. in 

 Acridiunij exhibit conditions which are very divergent from 

 those found in the Thysanura. By comparison with Machilis 

 (§ 29) and by a process similar to that adopted in the case of 

 the Isopoda it may be shown that the maxilla3, e. g. in For- 

 jicula, are composed of a first segment (cardo) without a lobe, 

 a second (transversely divided) segment with the masticating- 

 lobe, and a third (very obliquely cleft) segment with the galea, 

 together with a palpus proceeding from the third segment ; 

 the second and third segments with their four parts together 

 constitute the " stipes." (In the interpretation of the boundary 

 between the lobe and the segment in the case of the second 

 and third segments 1 have here on practical grounds not 

 followed the certainly more correct interpretation employed in 

 the case of the Crustacea, according to which the basal 

 division alone is termed tiie segment ; but the question has 

 the less interest since it only turns upon the determination of 

 the actual boundary between the segment and its lobe.) The 

 hypopharynx is well developed ; the maxillulas are still 

 present in various forms {e. g. Forficulidje and larvte of 

 Ephemerida*) as a lobe, which is attached to tiie skeleton at 

 the base of tlie hypopharynx. 



* A paper of mint' on tliis iinimal !>■ in'iu-ly vi'aily for tlio press. 



