PORPITA. 117 



Genus PORPITA. 



Pneumatocyst circular, produced into radiating lamellae inferiorly, but unprovided with a 

 crest. Tentacula branched.^ 



Forskal, whose powers of observation must have been of a very high order, not only 

 left behind the very recognisable figures of Velella (which he calls Holothuria denudata), given 

 in the 'Icones,' tab. xxvi, l, but his description (' Descriptiones,' p. 103) is admirable, and 

 contains everything that was known about the genus up to within a very few years. 



" Diameter latitudine digiti. Paginse superioris discus vel nucleus, diameter dimidio 

 minor ipsius animalis ; paulum elatus ut umbo clypei depressi ; albidus, striis concentricis et 

 e centro radiantibus decussatus, rigidus^ margine obscure ceeruleus. Limbus disco dimidio 

 angustior, cseruleus, immaculatus, pellucidus, flexilis, planus; linea circumcirca ad oram striis 

 nigris centrum spectantibus composita. Paginaj inferioris tentacula omnia, disco jam descripto, 

 nucleo scilicet, non limbo affixa. In medio apparet ventriculus limbi la itudine, basi globosus, 

 superne terminatus ore cylindrico aperto; quod demitti et dilatari potest patulum ejusdem 

 ambitus cum basi ventriculi ; ct conspectum dat intestinorum ; quae exserebantur gelatinosa, 

 albida, longa. ReliquBe parti albse nuclei adnectuntur tentacula parvula, leevia, basi ovata, 

 adunata in st3'lum filiformem apice incrassatum ; interiora tentacula alba ; exteriora magis 

 magisque CEerulescentia et pellucida, exeuntia ad limbi oram, non vero excedentia. Nuclei 

 margini cseruleo adnectuntur tentacula multorum ordinum, limbo longiora, inroqualia ; 

 exteriora seu superiora plerumque breviora ; quorum longissima dlametrum corporis parum 

 superant; brevissima vix limbum excedunt; omnia fiUforraia, hyalino cserulcscentia, linea media 

 obscuriore ; dimidia parte interiore nuda, dimidia exteriore triplici serie longitudinali ciliato 

 glandulosa, ad utrumque enim latus et subtus in medio exeunt pedicelli hyalino cserulescentes, 

 subverticillati, terminati glandula seu capitulo obscure caeruleo. Pedicelli atque capitula 

 versus apicem gradatim increscunt ; series infera terrainat tentaculum capitulo medio fere 

 sessili, inter glandulas laterales pedicellatas. Verticilli pedicellorum saepe 5 vel G in quovis 

 tentaculo. Varie incurvat animal etextendit tentacula glandifera ; at nuda ista contrahitssepe 

 in cylindros crassiorcs, apice patulos. Limbus interdum margine Iseviter reflectitur. In 

 fundo vasculi ubi Holothurias servavi vivas per horam unam alteramve, vidi ova an excre- 

 menta ? dejecta ; suhcubica, hyalina, cir cello fusco in medio baseos, et linea fusca subsinuata 

 interiore, erecta ad singulos 4 angulos laterales. Oculo tantum armato apparuere^ 



From the last passage it is clear that Forskal observed, without knowing it, the 

 detachment of the medusiform zooids of Porpita. 



Eschscholz ('System,' p. 176) calls the substance of the pneumatocyst of Porpila 

 "kalkartig" (calcareous), while that of Velella is termed "knorplig" (p. 168), without 



^ At any rate, provided with more or less stalked knobs or capitula. 



