26 



Characters. Head large with a well marked neck. Body stout, nearly equally thick 

 throughout, but tapering slightly towards head and posterior fin; firm, rather opaque. Longitudinal 

 muscles well developed. Tail segment 41 to 57 per cent, of the total length. 



A lateral epidermic expansion, forming an exaggerated collarette, reaches from the 

 widest part of the head to the post-septal fin, with which its outline in older specimens becomes 

 continuous: widest at or just before its junction with the fin. Fins commencing at the tail 

 septum, extending in mature specimens to the vesiculae seminales when tumid; generally rounded. 

 Tail fin truncate, reaching the vesiculae seminales when tumid. 



Jaws slender, at first nearly straight, then slightly curved ; the internal edge often 

 saginate for some distance about the middle of their length : the tips sharp, of medium size. 

 Anterior teeth with rather narrow bases; dark in colour. Posterior teeth long, slender, closely 

 set, dark in colour. 



Vestibular ridge with regular blunt spikes. Corona ciliata oval or hexagonal, lying 

 entirely on the neck and trunk. 



The following table has been constructed from 16 specimens. 



9.0 



44 



8.0 



43—50 



7-5 



46 



7.0 



43—57 



6.0 



4i 



8 9 ; 9 



8 — 9 8 — 9 12 — 16 



8912 

 7—9 7—10 11 — 15 



7812 



It may be doubted whether the differences between draco and Votigai are more than 

 matters of their respective ages (lengths). The smallest specimen which I assigned to draco 

 measured 5 mm. and was a giant compared to Beraneck's three specimens of 3 and 4 mm.; 

 its armature formula was 8:6:10, as against their 9 : 4 — 5 : 6 — 7. What at first seems to 

 be an important difference lies in the sharply curved tip of the jaw figured by BEraneck in 

 Vougai\ but the oldest jaws of young draco are often somewhat curved, and hardly exhibit 

 the sagination described above. Even with Zeiss Apochr. 4, oc. 8, I failed to see the points 

 figured by BEraneck at the tips of the teeth of draco; and believe that, as in other cases, 

 their appearance is due to wear and damage ; this, if true, would break down another distinction 

 between draco and Vougai. 



IV. Species incertae. 



? Sagitta furcata Steinhaus, and planetoids Steinhaus. 



O. STEINHAUS. Die Verbreitung der Chaetognathen im siidatlantischen und indischen Ocean. 

 Inaugural-Dissertation, Kiel, 1896, 8vo. 



Five specimens from deep hauls with the vertical net have been very doubtfully assigned 

 to these two species: regard being had to the armature (practically the same in both) and their 

 comparative firmness and flaccidity. The following table gives their stations and formulae. 



