658 CHOBDATA 



left and its ventral side at the right. The mouth (1) is at the forward 

 end and opens into the pharynx (3), from which the two ventro-lateral 

 stigmata (5) open directly to the outside back of the anus, there being 

 no peribranchial cavity and no cloacal pore. Most species are her- 

 maphroditic, the gonads lying in the hinder part 

 of the trunk. The tunic or '* house '^ is a trans- 

 parent envelope of large size, being sometimes 

 many times the size of the body, which is secreted 

 by certain large ectoderm cells called oikoplasts. 

 Within this tunic (Fig. 1,001) the animal can move 

 about freely : it is shed periodically and often, and 



Fig. 1,001— Appen- contains no cellulose, 

 diculanans in their 



H6?Juard)^^A^^oSko^ "^^^ appendicularians are found in all seas, 



pleura cophocerca; B, being usually more numerous at a distance from 

 Appendtculuna stcula, ° *' 



the continents. Most species live near the surface, 



but a few have been obtained at considerable depths. 



The class contains 2 families and more than 40 species. 



Key to the families of Larvacea: 



Oi Endostyle present. 1. Appendiculabiidae 



Oj Endostyle absent 2. Kowalevskiidae 



Family 1. APPENDICULARIIDAE. 



Pharynx with endostyle, from the forward end of which peripharyn- 

 geal ridges run dorsally and posteriorly and unite near the oesophageal 

 opening; heart present: 8 genera and over 30 species. 



Key to the genera of Appendiculariidae here described: 



Oi Trunk short and more or less oval. 



hi Tail about twice as long as trunk 1. Appendiculabia 



h. Tail several times as long as trunk 2. Oikopleuba 



o. Trunk very long 3. Fbitillabia 



1. Appendicularia Fol. Trunk short, compressed anteriorly ; tail 2 or 

 3 times as long as broad and twice as long as the trunk ; endostyle straight 

 or slightly curved ; intestine turned to the right and bent round the very 

 large vesicular rectum; anus on the right; ovary round, surrounded by 

 the horseshoe-shaped testis : 1 certain and several uncertain species. 



A. sicula Fol. (Fig. 1,001, B) . Mediterranean Sea and Atlantic Ocean. 



A. longicauda Vogt. Long Island Sound to Massachusetts Bay. 



2. Oikopleura Mertens (Fig. 1,000). Trunk oval; tail from 2 to 

 6 times as long as broad and from 2 to 4 times as long as the trunk; 

 digestive tract very large, with a curved oesophagus and a bilobed stom- 

 ach; gonads very large; testis usually paired and one on each side of 

 the median ovary: 14 species. 



