ZOOI.CXiK'AI. SOCIKTY BULLETIN 



opening leads into a capacious pharynx, pro- 

 vided with numerous slit-like gills. There any 

 microscopic food which the water may contain 

 is separated out and passed into the coiled 

 or looped intestine. A current of water, pro- 

 duced by the action of cilia on the walls of 

 the pharynx, jjasses through the gill openings 

 into the atrial cavitj- within the tunic and to 

 the outside by another opening, the atrial pore, 

 which is situated near the mouth. The intes- 

 tine ends in the atrium near the pore and the 

 current of water sweeps out the excretae. Of 

 course the looped form of the intestine and the 

 position of the incurrent and excurrent open- 

 ings near together on the upper surface are 

 merely adajjtations to the mode of life. The 

 same conditions are observed in the Bryozoa, 

 Sipunculoid worms and numerous other at- 

 tached and tubicolous forms of animals. 



The sex cells, when ripe, may be carried out 

 also by the excurrent stream of water, or, in 

 other cases, the eggs may be retained in the 

 atrial cavity, where they undergo development, 

 and finally the free-swimming larva, resem- 

 bling small tadpoles, are released through the 

 atrial pore. These swim about for a short time 

 to distribute themselves, and to find some solid 

 substance to which they may become attached 

 by a special adhesive disc and so remain fixed 

 for the rest of their lives. The metamorpho- 

 sis takes place immediately after they become 

 attached. In this process the tadpole-shaped 

 larva loses the tail and notochord, develops the 

 tunic and takes on the form of the adult. 



The tough tunic seems to be an ample pro- 

 tection, for, in spite of their numbers, few 

 animals ever seem to feed on them. Undoubt- 

 edly some fishes are able to bite through the 

 tough cover, but they must be disappointed 

 at the small amount of nutriment to be obtained 

 as the result of their labors. 



Molgula often occurs in such numbers as to 

 cover the surface of piles, rocks, etc., with a 

 close layer and may be obtained in large quan- 

 tities for the purpose of study. 



A larger form, Boltenia, occurs in somewhat 

 deeper water oflf our coast. This ascidian has 

 a long stalk w'ith a grapple-like expansion at 

 its base for attachment and an oval enlarge- 

 ment or body at the upper end, giving the 

 animal somewhat the appearance of an Indian's 

 warclub. a resemblance further borne out by the 

 size, as it grows to be nearly a foot high. It is 

 often richly colored. When red it is known 

 to the fisherman as a "sea ))eaeh." when yellow- 

 ish, as a "sea lemon." 



The compound ascidians are always smaller, 

 and are either developed at intervals on a 

 stolon, sometimes resembling miniature melons 

 on a leafless vine, or they may be closely set 

 ,ind embedded in .i jelly-like mass forming a 

 common tunic for the colony. .">ome of these 

 form considerable masses, either spreading over 

 rocks, shells or piles or sometimes growing erect 

 in masses or strands even to the height of a 

 couple of feet. The colon)- figured was 1.5 inch- 

 es high. The small areas showing on tiic sur- 

 face represent clusters of one-half dozen to two 

 dozen individuals. The writer has dredged them 

 u)) by the bushel from the bottom of Vineyard 

 .Sound. These masses are known to the fisher- 

 men as "sea pork," or are often mistaken for 

 sponges or what not. Some of the clustered 

 forms were known among others to the ancients 

 as "sea grape" or "sea fruit" — the "uva marina" 

 of Pliny. Rondelet, 1554 (De Picsibus Ma- 

 rhii.i, p. 130) and Gesner, 1587 (Historia Ani- 

 mal iiim, p. lOil) figure such a sea fruit or "uva 

 marina" which is undoubtedly a colonial ascid- 

 ian. Pliny is responsible for the remarkable 

 statement, — which one may disbelieve if he 

 chooses, — that sea grapes rotted in wine and 

 drunk cause a loathing of wine thereafter in 

 drunkards on acount of its fetid marine odor. 

 The ancients believed that "like cures like" 

 {".similia similibus ciirantur") and did not hesi- 

 tate to apply heroic remedies. 



One genus, Boiri/lliis, is of frequent occur- 

 rence at the Aquarium, growing in a thin layer 

 on the wall of a tank or the sides of a glass 

 jar and occasionally spreading over nearly a 

 stjuare foot of surface. It often encrusts the 

 le.ives of eel grass and other sea weeds in shal- 

 low water with its slimy layer. 



In another species. Amaroiicinm pelluciditm, 

 the jelly-like mass is often impregnated with 

 sand to such an extent that it is rendered quite 

 firm. This species was originally described as 

 .1 bryozoan. The accompanying figure repre- 

 sents a colony six inches in diameter, dredged 

 by the writer in Vineyard Sound. 



.\11 together about thirty s])ecies of these 

 tuuic.ites occur in the neighboring waters. 



The Thaliacea or salps which constitute the 

 third group of the Tunicata are entirely jielagic. 

 While at first they ajipear to have no similarity 

 to the sessile sea-squirts, the differences can be 

 explained for the most part by the difference 

 in the mode of life. That an animal which 

 s))ends its whole life time swininiing at or near 

 the surface of the ocean must be constructed 

 on a different plan from one that remains in 

 one place attached to the sea bottom seems 



