240 On Plankton CJuetognatha from New Zealand. 



liavdlj possible. Two species of tlie orenus, P. pi'sum (L.) 

 and P. novce-zealandiat, Filhol, are mentioned in Hutton's 

 ' Index Faun?e Novai Zealandige ' (1904, p. 250). I am not 

 aware of any observations on the swimming-powers of the 

 males, but the occurrence of a specimen in a tow-net gathering 

 is unexpected. 



II. CII^TOGNATHA. 

 By G. Herbert Fowler, B.A., Ph.D. 



Two specimens only occurred in the collection, both in 

 haul 1 A. They were immature, sliowing neither ovaries 

 nor testes, and no trace of the corona ciliata was left. 

 Formula3 * : — 



10 25 8 3 3 



10 23 9 3 2-3 



While the formulas and the flaccid body suggest hexaptera, 

 the presence of a neck-constriction beliind the head and the 

 apparent extension of the lateral fins are against this deter- 

 mination ; further, the tips of the jaws are clearly not of 

 liexapteran type. On the other hand, no species, even at 

 10 mm. in length, has been recorded with so few teeth. The 

 specimens seem pretty clearly to belong to an undescribed 

 species, but it is eminently undesirable to give a name to 

 two immature examples. In the hope that further specimens 

 may be captured elsewhere in Southern Seas are appended 

 the diagnostic characters : — 



Head small, separated from the trunk by a neck- Q 

 constriction ; no collarette present. Body flaccid, 

 thickest about the middle of the total length, 

 tapering gradually forwards, diminishing rapidly 

 near the tail-septum. Longitudinal muscles broad 

 but weak, lateral flelds narrow. Tail-segment 

 narrow, 23 to 25 per cent, of the total length (in- 

 cluding tail-fin). Anterior fins long, (?) widest 

 about the middle of their length, reaching ante- 

 riorly to the ganglion, posteriorly almost to the 

 posterior fin. Posterior fins fairly long, (?) about 

 as wide as the anterior fins, widest in front of tiie 

 tail-septum ; about two thirds are on the trunk 

 and one third on the tail. Jaws slender, the oldest 

 with slightly curved tips; tip small. Vestibular ridge unde- 

 veloped; corona ciliata not seen. 



* For these and the terminolog'y employed should be consulted 

 ' Siboga ' Expedition, Report on the Cheetognatha, by G. Herbert Fowler. 

 Leiden, 190G. 



