230 



MR A. PRINGLE JAMESON ON THE 



Horizontal distribution : 49 25' S., 9 21' W.-69 22' S., 26 36' W. 



Vertical distribution : 800 fathoms-surface. 



Temperature range : 28'9-39 F. 



Stations : 273, 280, 448, 325 (2) vertical net 23/3/04, 422. 



? Heterokrohnia sp. (Kitter-Zahony). 



A single specimen taken in a vertical -net haul might possibly belong to this genus ; 

 the state of preservation, however, will not admit of any certain determination. 



The body is slender and firm. Transverse muscles are developed both in the trunk 

 and in the tail. The lateral fins are almost totally destroyed, but there does not seem 

 to have been more than one pair. The tail fin is also much damaged, but it appears 

 to have been somewhat rounded and is very full of fin-rays. The percentage of tail 

 to body length is probably about 25 '6; the lowest percentage given by RITTEK- 

 ZAHONY (1911) is 32'3. The head is not well expanded, so that the teeth and anterior 

 portion are not well seen. There are certainly not fewer than 14 posterior teeth. 

 There are at least 1 1 jaws, rather long, slender, and knife-like, and only slightly curved, 

 in general somewhat like a scythe blade. 



On the whole, these features are those given by PaiTER-ZAHONY in his diagnosis of 

 this new genus Heterokrohnia. Indeed, the presence of transverse muscles in both 

 trunk and tail would seem to be enough to determine the genus. It is, however, 

 impossible to determine the species. The only species described is H. mirabilis, 

 characterised by a high tail-percentage, and very numerous anterior and posterior 

 teeth. This specimen does not show these features clearly enough to warrant any 

 statement being made as to the species. 



Taken in a vertical net on February 29, 1904, at Station 398, 68 25' S., 

 27 10' W. Surface temperature 30 F., and temperature at 1000 fathoms probably 

 about 32 F. 



Krohnitta subtilis (Grassi). 



Specimens of this species were not abundant ; it was found in only seven samples, 

 and there only in small numbers. The explanation of this apparent rarity is probably 

 to be found in the fact, pointed out by FOWLER (1906), that this is a species which has 

 its habitat in cooler waters of the "lower epiplankton and upper mesoplankton," 

 seeming to avoid " the warmer surface water." One would naturally expect that such 

 a form would be taken only rarely in surface tow-nettings. Further, the specimens 

 obtained were all very evidently young forms, the largest being 5'5 mm. in length. 



(ROY. soc. EDIN. TRANS., VOL. XLIX., 988.) 



