CLASSIFIC.VTIOX OF THK TUNICA.TA. 647 



Pegea, Savigny, 1816. 



Branchial sac having rudimentary stigmata on its dorsal 

 edge, alongside the dorsal lamina. 



Alhnentary canal coiled up to form a " nucleus." 



Gemmation results in a ribbon-like band of aggregated forms. 



Single embryo develops at a time. Ft is not covered. 



In other particulars like Salpa. 



This section contains the single species Pegea scutigera- 

 confoederata*, Cuv.-Forsk. (AtL, Pac, Ind. 0., Med.). 



lASist {Savigny, 1816), Lahille, l^QO. 



Alimentary canal closely coiled up to form a " nucleus." 



Gemmation results in a ribbon-like band of aggregated forma. 



Embryos 2 or 3 in number at a time. 



In other particulars like Salpa. 



This section includes ihree species : — 



fWith no large appendages at posterioi* end in solitary form. Aggre- 

 I gated form witii anterior end narrower than posterior. 

 J /. cordiformis-zonaria, Q. & G.-Pall. 



I [(Atl.. Ind. O., Pac, Med.) 



1 With a pair of large appendages at posterior end in sol. form. 



1^ Agg. form with anterior end wide 1 



/'Appendages plain, directed latei-ally, no lougit. ridges on test. Agg. 

 i form with aperts. terminal. I. costata-TUesii, Q. & G.-Cuv. (Atl.) 

 \\ [Ind. 0., Pac, Med.) 

 I Appendages serrated, directed posteriorly and terminating longitudinal 

 (^ ridges of test. Agg. form with apertures dorsal 2 



(Muscle-bands wider than the interspaces in agg. form, 

 I. he-xagona\, Q. & G. (Pac, Ind. O.) 

 Muscle-bands much narrower than mterspaces ; only agg. form known. 

 /. nitida, Herdm. (Pac.) 



Most of the remaining species of JSalpidae which have been de- 

 scribed or figured have been shown by Traustedt, or others, to 



* Salpa quadrata, Herdm. (N. Atl.), appears to be closely related to this 

 species. The single ' Challenger ' specimen (sol. form) had a remarkable club- 

 shaped dorsal lamina ; but that may be an individual abnormality. 



t This, however, is not the lasts of Savigny, the type of which was Salpa 

 cylindrica. 



I Salpa musculosa, Herdm. (Atl.), and S. cchinata, Herdm. (Atl., Pac), are 

 probably clcsely allied to this species; but as the condition of their embryos is 

 not known, they cannot be placed with certainty in this genus. The solitary 

 forms only are known, and they differ in several particulars from that of 

 lasis hexagona. 



LINN. JOURN. ZOOLOGY, VOL. XXIIT. 46 



