authors for Porpitidae, and he comes to the conclusion that a great many Atlantic and Mediter- 

 ranean forms should be reckoned as only one species, Porpita tinibella. The different synonyms 

 show what a large number of species have been founded. As well as for the Indian and for 

 the Pacific species, the nomenclature is exceedingly extensive. 



As regards Po7'pitidac the Siboga material is entirely insufficient for real anatomically or 

 even morphologically thorough description. In some specimens the naked disk only has remained, 

 in others nearly all the appendages are lost and the colours of course are all gone. Comparing, 

 however, these poor remains with Agassiz' complete description 83 we found no difference what- 

 ever between them and Porpita Linfiaeana, and as Chun also regards this species as Porpita 

 umbella^ we use also here the same specific denomination for the twenty incomplete specimens 

 of the Siboga expedition. 



Diameter of the disk varies from 5 mm. to 23 mm. Chux finds the measurements 

 4 — 20 mm. 



Fam. Velellidae Brandt 35. 

 Velella Lamarck 1801. 

 62. Velella pacifica Eschsch. 29. 



Stat. 223. Lat. 5°44'.7S., Long. 126° 27'. 3 E. Cat. 123. ale. 9o7o- One specimen. 

 Stat. 226. Lat. 5°26'.7S., Long. i29°36'.5E. Cat. 112. ale. 90°/^. 4 specimens. 



The five specimens from the Siboga expedition are small and young and their appendages 

 are very insufficiently preserved. A characteristic of J 'e lei la pacifica given by Eschscholtz is the 

 triangular shape of the crest ; this is also the case in all our specimens. The crest is moreover 

 in all specimens a "Northwestern" one; that is to say, if we take the specimen before us, with 

 its longer side in front the crest goes from South-east to North-west. This seems to be rare 

 in Velellidae^ as Chux amongst his material found 71 South-w-estern against 6 North-western, 

 and amonost Agassiz" material there was not one North-western. 



