CRI'STACKA MALACOSTRACA. III. 



According to Sars' figures of the animals from above, /. hirtictps and /. it< ntnulatu differ ex- 

 tu inch in the armature with spines on the anterior margins of the four anterior thoracic segment*, 

 and must therefore be easy to separate. But the examination of a large material from numerous 

 places showed that /. drnticulata must be cancelled, as already stated by Ohlin (1901); I found spe- 

 cimens agreeing with /. hirticeps and others agreeing tolerably well with /. J>-nticut<it<t, but many 

 specimens showed intermediate features, and neither depth nor temperature at the bottom seems to be 

 ! real influence on the development and character of the spines mentioned. Some particulars on the 

 variation may be of interest 



The largest specimen, a female from the cold area ("Ingolf" Stat 126, 293 fath.) is 10-5 mm. 

 Ion);; it has nearly thirty spines, many among than moderately large, along the front margin of second 

 segment A large specimen from Stat 103 (579 fath., temp, -j- 0-6) has about twenty-two .-.pirns <>u 

 the same margin, and in a small specimen, 3-4 mm. long, from the same station the marginal spines are 

 in nch less numerous, though very conspicuous. In a specimen 6-2 mm. long from Stat 139 (702 fath., 

 temp. -4- 0-6) the spines on the margin of second segment are somewhat small and only twelve or fourteen, 

 while the head is almost smooth; in a smaller specimen 4*5 mm. long, from the same station, the head is 

 i|iiite smooth and the marginal thoracic spines few and feebly developed. My largest specimen from tin 

 warm area, a female from Stat 24 (1199 fath., temp. 2-4 i, is 8 mm. long, has nearly thirty well developed 

 spines on the anterior margin of second segment, and is completely similar to large specimens from 

 the cold area; another female, 7 mm. long, from Stat 24 has only sixteen or eighteen spines along 

 the same margin and several among them large; a third specimen, 4 mm. long, from the same station 

 has six large spines on the same margin. In specimens 67 mm. long from south of Iceland I. .it 

 63i5' N.) I find the anterior margin of the four segments extremely finely crenulate, the microscopic 

 teeth being more numerous than according to Sars figure of /. hirticcps, and, besides, set with a small 

 number of irregularly distributed, moderately strong spines, but probably some other spines have lu-cn 

 broken off; in specimens 4-55 mm. long from the same place the fine crenulation is well developed, 

 but no real spines are found, while the head has as usual numerous spines. In specimens 67 mm. 

 long from another place in the warm area, viz. south-west of the Faroes in Iat 6ii5* N., the fine 

 crenulation is very distinct, but scarcely any spine could be detected on the margins. In very juve- 

 nile specimens, from 2-5 to 3 mm. or rarely nearly 4 mm., the spines on the head and spines or crenu- 

 lation on the margins of the four anterior segments are sometimes partly or totally undeveloped. 



All specimens, excepting the most juvenile, are distinguished from /. dubia n. sp. in having 

 the head conspicuously broader than first segment about as broad as, or frequently broader than, se- 

 cond thoracic segment /. hirticeps is separated from /. longicomis G. O. S. (-- /. /Y nkttti Tatt) in 

 having the basal joint of the antennulae (fig. 7 a) armed with a few or several spines on the outer 

 margin, and, besides, this joint is proportionately longer than in /. bngtcornis. (Above, on p. lai, it has 

 been mentioned that in Sars' main figure of /. dfttticulata the basal joint of the antennulae is correct, 

 while it is wrong in his figures of /. longicornis and /. hirticeps.} Of /. longicornis one of the largest 

 specimens is 4-7 mm., thus considerably larger than according to Sars, who said -about 3 mm."; 

 adult specimens oi this species are rather similar to specimens of the same size of /. hirticrps. but can 



be distinguished by first antennular joint and by having no spines on the head and no vestige of 



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