270 THE VOYAGE OF H.M.S. CHALLENGER. 



families Bolteninae and Styelinae range into deep water, while the Cynthinse are all found 

 in less than 40 fathoms. Among the Bolteninae, Boltenia is from shallow water, while 

 Culeolus is a peculiarly deep-water genus, but has a considerable range, viz., from 630 to 

 2425 fathoms. Five of the species are from upwards of 1000 fathoms, four from over 

 1500, and two from upwards of 2000. Thus they all belong to the abyssal fauna. 

 Fungulus, which is closely allied to Culeolus, is also a deep-water form. 



Iu the StyelinaBj Styela has a range of from shallow water up to 2600 fathoms. 

 Five species belong to the abyssal fauna, three of them being from 600 fathoms, and two 

 from 2600. The remaining species of the genus are all from less than 150 fathoms. 



Polycarpa is a shallow-water genus, ranging from quite shallow water to 150 fathoms, 

 and therefore having no representative in the abyssal zone. The remaining genus of the 

 Styelinse, Bathyoncus, is the only peculiarly deep-water genus in the sub-family. It was 

 found at a depth of 1600 fathoms. 



In the Ascidiidae the majority of the species are from small depths, but two genera, 

 Corynascidia and Abyssascidia, are peculiar to very deep water, while two species of 

 Ascidia (Ascidia meridionalis and Ascidia tenera) also range into the abyssal zone. 

 The remaining species are distributed from shallow water up to 150 fathoms. The species 

 of Corella, Pachychlcena and Ciong are from depths of less than 100 fathoms. 



If the range of depth at which Simple Ascidians were found (from the shore down to 

 2600 fathoms) be divided into five zones, the following results will be arrived at : — 



I. — Between the shore and 50 fathoms forty-seven species were found, viz. : — 



Molgula gregaria. 



horrida. 



forbesi. 

 Eugyra kerguelenensis. 

 Boltenia legumen. 

 Microcosmus h elleri. 



propinquus. 

 polymorphus. 

 Cynthia hispid a. 



cerebriformis. 



Jissa. 



formosa. 



arenosa. 



irregularis. 



complanata, 



pallida. 



papietensis. 



