Limbs and Mouth-parts of Crustaceans and Insects. 423 



in water [not glycerine] and taken from large specimens 

 which have been preserved for some time in fairly weak 

 alcohol ; they can, however, also be observed in ordinary 

 glycerine preparations.) An examination of older prepara- 

 tions (most kindly lent to me by Prof. Claus) of Paranehalia 

 longipes, W.-S., displayed no especially distinct conditions, 

 yet in a pair of appendages I observed the small basal 

 segment. In Sars's figure of the last pair of limbs this basal 

 segment may be seen divided off on the outer margin (' Chal- 

 lenger ' Report, vol. xix.) ; if we reckon two more segments 

 for the epipodite and exopodite we get nine segments, since 

 the figure alluded to shows beyond the base of the exopodite 

 six segments, of which the last is very short (I have con- 

 vinced myself of its existence in some legs from Claus'.s 

 preparations). 



17. The first segment of the maxillula bears a masticating- 

 lobe of considerable size, which is articulated to it near the 

 base ; the second segment has only a narrow rigid plate of 

 chitin and is destitute of the masticating-lobe ; the third 

 segment passes insensibly into a short broad lobe. These 

 conditions can be very easily observed if the muscles are to 

 a certain extent removed. (The composition of the maxillaj 

 I have not been able to determine with certainty.) 



/3. EUMALACOSTKACA (§§18-27). 



18. Mysidce. — The antennae have a six-jointed stem (cf. 

 Nebalia, § 15) ; the outer ramus (squama) arises from the third 

 segment {cf. Copepoda, § 10). The mandibles have a 

 " lacinia mohilis " (for the explanation of this term see 

 Hansen, " Cirolanidae"). As in Nebalia, the two lobes of 

 the maxillulaj spring from the first and third segments [vide 

 " I'ijmphna-Togtet "). The lobes of the maxillte arise from 

 the second and third segments (the boundary between tiie 

 first and second segments is incorrectly indicated in " Dijm- 

 phna-Togtet ") and the exopodite from the third segment. 

 The first segment of the feet has disappea'^ed, so that the 

 exopodite springs from the second segment ; the foot there- 

 fore consists of eight segments [cf. § IG), for I regard the 

 claw as a modified segment, or, in other words, the terminal 

 segment has become cheliform ; tiie basal segment is much 

 shorter than the second ; the " knee," where the chief move- 

 ment in a vertical direction takes place, is found between the 

 fifth and sixth segments (Boas). In the earliest stages of 

 the larva we find at the end of the abdomen two somewhat 

 firmly chitinized, narrow, hard processes (van Beneden, 



