ZOOLOGICAL SOCIETY BULLETIN 



axiomatic. Yet that these differences need not 

 be fundamental, is shown by the structure and 

 development of this and the foregoing group of 

 tunicates. 



The meaning of the common name "salp" is 

 not clear. The term is very ancient, for Pliny 

 used "salpa" in reference to a kind of stockfish 

 (fish dried without salting). Whether the diffi- 

 culty of getting any nutriment out of this sort of 

 stockfish, which had to be soaked and beaten 

 before it could be eaten, led to the term "salp" 

 being facetiously applied to these tough and in- 

 nutritious ))elagic tunicates seems at least a 

 possible interpretation. 



The individual salp resembles a miniature 

 cask with both ends knocked out. The wall con- 

 sists of the tough transparent tunic, through 

 which appears a series of circular muscle bands 

 resembling hoops, which are, however, on the 

 inside instead of outside. The open ends are 

 necessary to the mode of locomotion, which is 

 altogether unique. Water is taken in at the 

 anterior aperture and a wave of constriction 

 runs over the circular muscles, each in turn 

 narrowing the diameter of the tube and forcing 

 the water backward and out of the posterior 

 opening. This process causes the salp to move 

 slowly forward, much as though it were actually 

 drinking its way through the water. In its 

 course through the body the water passes over 

 the gills and supplies oxygen, and food is also 

 removed and carried into the intestines by the 

 action of cilia. 



These animals are occasionally so numerous 

 in the summer months that they seem to fill the 

 ocean for many miles, so that dozens or even 

 hundreds may be dipped up with every bucket 

 of water. Sometimes they are thrown on shore 

 in countless numbers. They are often highly 

 phosphorescent. 



Our commonest species in this region is S. 

 zonaria — cordiformis. As a rule the salps are 

 about an inch or so long by nearly half as broad. 

 One larger species, Salpa tilesii — costata reach- 

 es a length of eight or ten inches and appears 

 to be rare. A single specimen from Matinicus, 

 Me., sent to the Aquarium last year for identifi- 

 cation, was taken in a lobster pot at a depth of 

 20 fathoms. This is much farther north than it 

 has hitherto been reported on this coast. 



Among the interesting features of this group 

 is a peculiar mode of reproduction by alterna- 

 tion of generations. There are two types of 

 individuals, usually quite unlike one another, so 

 that in most cases they were given different 

 names before their connection was suspected. 

 The hyphenated specific names, like those given 



above, are not therefore indicative of aristocra- 

 cy, though the salps are no doubt a very ancient 

 family, but merely show that these names have 

 been ap))lied to the two generations of the life 

 cycle. One of these, the solitary generation, 

 occurs singly, and reproduces asexually by 

 forming a string of buds, which develops into 

 a string of aggregate or chain salps. These, 

 wiiich form the second or sexual generation, are 

 attached side by side, often in long strings look- 

 ing like well-filled, transparent cartridge belts. 

 Each individual of the chain develops sexual or- 

 gans and produces eggs which may give rise 

 to tadpole larvae or may develop directly into 

 the adult solitary asexual form. Reproduction 

 goes on with great rapidity in the warmer 

 months, hence the appearance of enormous 

 numbers in middle and late summer. 



Porpoises. — At one time in the month of 

 October the Aquarium had in the building speci- 

 mens of three different genera of porpoises, 

 two of them alive and on exhibition, the third 

 having arrived dead. One of these was the 

 fine Ttirsiops eight feet long, received from 

 Hatteras, N. C, in November, 1913; another, a 

 Delphiniis seven and one-half feet long from 

 Seaside Park, N. J., and a Phocwna, four feet 

 long, from Provincetown, Mass. 



The Delphinus, like other porpoises captured 

 by fishermen, did not live long. The Phoco'na, 

 called harbor porpoise, is the smallest of the 

 porpoises which inhabit our coast, seldom ex- 

 ceeding five and one-half feet in length. It is 

 also the commonest, entering harbors freely, 

 where it is often called "herring hog" and 

 "puffing pig." 



It is a pleasure to record again the good 

 health and liveliness of our bottle-nose porpoise 

 {Tursiops truncalus). which has now completed 

 its fifteenth month in the building. 



We are unable to detect anything like dis- 

 content in its conduct and have never had a 

 more expensive boarder. It consumes twenty- 

 five pounds of fish a day, and would take more 

 if supplied. Whatever the market affords 

 cheapest, butterfish, weakfish or herring, is 

 taken promptly, provided it is fresh. 



We have watched this endurance test of the 

 porpoise in captivity with great interest and 

 not without misgivings. It is most gratifying 

 to see this ranger of the ocean adapt himself to 

 restricted quarters with apparent contentment. 



C. H. T. 



