584 PBOr. W. A. HEEDMAN S EETISED 



.0/2 or 3 stigmata in a mesh P. procem, Slait. (Mai.). 



•^ [4-10 stigmata in a mesh 20 



r Siphons very long P. lofiffisiphonica, ^erAm. (Austr.) 



^^ I Siphons not unusually long 21 



„. r Test prolonged into branched hair-like processes 22 



[Test not provided with these processes or fibres 23 



(Apertures close, conspicuous, yellow speckled with red. 

 P. comata, Aid. (N.W. Eur.) 

 Apertures distant, inconspicuous, dark brown colour. 

 P. molgidoides, Herdm. (Austr.) 



f Individuals very small, like pellets of sand. 



23 \ ^. pilella, Herdm. (S. Atl.) 



[ Individuals not small 24 



r Test having processes for attachment ; tentacles 16-20. 



24 J P. sabulosa,lldl&r. (Me3.) 



[ No processes of test for attachment present 25 



nr r Atrial aperture at anterior end ... P. tindor, Q. & G. (Austr.) 

 I Atrial aperture at posterior end... P. Stimpsoni, Heller. (Austr.) 



■,„ /Dorsal lamina a plain membrane 26 



\ Dorsal lamina not a plain membrane 27 



{Dorsal lamina ribbed only in the anterior part. 

 P. captiosa, Sluit. (Mai.) 

 Dorsal lamina with partial ribs aloug the entire length. 

 P. /wmosa, Herdm. (N. Atl.) 



/Tentacles numerous, 60 or more 28 



I Tentacles not numerous, 40 or less 29 



(Dorsal tubercle irregularly horseshoe-shaped, one horn turned out. 

 P. rugosa, v. Dr. (S. Atl.) 

 Dorsal tubercle nearly circular, horns turned in. 

 P.pomaria, Sav. (N.W. Eur.) 



on /Body free, covei'ed with sand, &c 30 



\ Body attached, test exposed or only partially incrusted 31 



{Surface smooth, regular, fine sand gi-ains ; colour yellow-brown. 

 P. curta, Hei-dm. (N. Atl.) 

 Surface rough, irregular, stones &c. attached ; colour dull yellow. 

 P. monensis, Herdm. (N.W. Eur.) 



r Test cartilaginous, with bladder-cells. 

 31 -I P. ascidioides, n. sp. (Austr.) 



[ Test not cartilaginous, no bladder-cells 32 



0.7 r Test quite black 33 



1 Test not black 34 



1 Fixed by shaggy fibres, foreign matter attached. 

 P. obscura, Heller. (Austr.) 

 Test with no fibres, surface free from foreign matter. 

 P. cryptocarpa, Sluit. (Mai.) 

 {Body discoid, flattened antero-posteriorly, tentacles 16. 

 P. discoidea, JLeWev. {ISIleA.) 

 Body not flattened antero-posteriorly 35 



f Surface nearly smooth 36 



\ Surface irregular and crumpled, or mamillated 37 



„,. f Shape ball-Uke P. femeVZa, Heller. (W. lud.) 



"*" 1 Shape not ball-like 38 



og /Posterior end narrow 39 



\ Posterior eiad broad and rounded 40 



27 



26 



28 



35 



