56 PROFESSOR GEORGE H. CARPENTER 



The remarkable genus Cryptopygus, showing affinities to Anurophorus and to 

 Isotoma, was erected by WILLEM (1902) for a new species of springtail (C. antarcticus) 

 found in numbers on the shores of Danco Land and the neighbouring islands.* The 

 present species from the South Orkneys is very closely related to WILLEM'S insect, 

 differing chiefly in having only twelve ocelli (instead of fourteen), and in the compara- 

 tively short and stout mucro of its spring. In the adult C. crassus the six ocelli on 

 either side are arranged in an anterior triangular group of three and a posterior curved row 

 of three (fig. 16), (the fourth ocellus, nearest to the centre of the head, which is present 

 in C. antarcticus. being here absent). In the very young C. crassus the six ocelli are 

 more closely grouped (fig. 15). These very young individuals (fig. 13), only - 5 mm. in 

 length, have the violet pigment mottled over their bodies, contrasting strongly with 

 their almost black parents. The springs of these young especially the dentes and 

 mucrones are shorter and stouter than those of the adults (figs. 21, 22, 23). Among 

 the adults the males may be distinguished from the females (fig. 14) by their more 

 slender form and more elongate feelers (fig. 16). In the male these have the terminal 

 segment half as long again as the third, while in the female there is no appreciable 

 difference in length. The antennal organ consists of a single papilla at the extreme 

 tip of the terminal antennal segment (fig. 16, a. o.).f 



In the excessive reduction of the hindmost abdominal segment (fig. 14, abd. vi.), 

 retracted and almost hidden in a depression of the genital segment (fig. 14, abd. v.), 

 C. crassus agrees closely with C. antarcticus as described and figured by WILLEM. 

 This character gives the name to the genus. 



Examination of the mouth-parts of C. crassus (figs. 18-20) shows that they conform 

 to the type usual in the Collembola. The mandible is very slender at the tip, which 

 bends markedly towards the centre of the head (fig. 18, ap.) and ventralwards (fig. 20) ; 

 the apical teeth are feeble and close together. On the outer edge of the mandible, 

 opposite the grinding surface (figs. 18, 20, mo.}, is a characteristic prominent shoulder 

 (fig. 18, hu.), and the conical process (for attachment of a rotatory muscle) on the 

 dorsal aspect of the base of the mandible (fig. 20, pro.) is also prominent. 



The maxillulse (fig. 19, mxl.) are simple in form, with a few minute bristles at the 

 tip or their inner faces ; the arm (fig. 19, br.) which supports the maxillula is bent and 

 irregularly furcate in shape. It is connected by a ligament (fig. 19, lig.) with the outer 

 framework of the maxillula, this being itself continuous with the inner chitinous rod 

 of the maxilla (fig. 19, rh. int.), as explained by FOLSOM (1899) for Orchesella. 



The maxillae (fig. 19, mx.) are of the typical Collembolan form ; the palp, however, 

 is remarkable on account of the production of its tip into a tongue-shaped process 

 bearing four bristles, and the excessive development of the long proximal bristle and 

 its papilla (fig. 19, pa.), 



* Recorded by WAHLOREN from South Shetland, Graham Land, Paulet Island, and South Georgia, 

 t Cryptopygus cinctus, newly described by WAHLGREN (1906) from Tierra del Fuego and East Falkland, has, like 

 C. crassus, only twelve ocelli, and no clubbed hairs on the feet. It is, however, variegated in coloration when adult. 



(ROY. SOC. OF EDIN. PROC., VOL. XXVI., PP. 476-478.) 



