386 LOWER FORMS OF MARINE LIFE 



last more than a couple of hours, the worms after this apparently sinking to the 

 bottom exhausted. 



In connection with the swarms of these worms, mention may be made of a 

 remarkable phenomenon seen on the Californian coast a few summers ago. Early 

 in July a red streak was noticeable in the sea off San Pedro Harbour, which 

 during the next few days approached the shore and divided into several patches 

 of many acres in extent. On the 16th the patches reached the shore, where 

 they were the cause of the most unusual display of phosphorescence. This dis- 

 coloration and phosphorescence of the water were due to the presence of swarms 

 of flagellate animalcules. Four days after the red streak reached the shore, a 

 most sickening odour arose from the water along the beach. During the night, 

 on a beach about 400 feet long, a large number of animals were left by the tide; 

 among them being several hundred holothurians, several specimens of two species 

 of sting-ray, two of beaked rays, two dog-fishes, a red perch, a large number of 

 smelts, and several octopuses. The ' red water ' occurred for at least two hundred 

 miles along the coast and extended several miles out to sea ; it had not disappeared 

 at the beginning of September. Wherever it occurred food-fishes were scarce, 

 but the small harbour-fishes and invertebrates of the ' plankton ' were unaffected. 

 Towards the end of July the animalcule Noctiluca appeared in swarms and 

 devoured the animalcules of the red water. A somewhat similar visitation is 

 reported to have occurred five hundred miles farther south in the seventies of the 

 last century. 



It may be added that the so-called sea-mouse {Aphrodite aculeata), of the 

 British seas, which grows to a length of from three to six inches, and is remarkable 

 on account of its iridescent bristles, is a member of the annelid class, to which 

 belong also the tube-worms (Sabella), which encase themselves in tubes of sand 

 and fragments of shell, great colonies of these being aggregated into a rock-like 

 structure. 



sea-Lilies, sea- Till a comparatively recent date the sea-lilies, or crinoids 



Urcbins, etc. (Crinoidea), were supposed to be an almost extinct group, but 

 deep-sea dredging has revealed the existence at the present day of a large number 

 of these beautiful organisms in the ocean depths. Crinoids consist of a long slender 

 stem formed of a number of calcareous discs with a central axis of organic sub- 

 stance, which is attached by its base to the sea-bed. At the summit of the stem is 

 a cup, or calyx, from which radiate a number of arms, also composed of calcareous 

 joints, and surrounding the central cup. Most crinoids are fixed throughout life ; 

 but there are certain species, such as the British feather-star (Antedon rosacea), in 

 which this fixed condition is only temporary, the cup and its arms becoming in 

 the adult condition detached from the stem, so that for the rest of its life the 

 organism is free-swimming. Among the modern fixed types of sea-lilies, it may 

 be mentioned that the genus Pentacrinus is very ancient, dating from the Jurassic, 

 or Oolitic, period of geological history. Other genera have been named Rhizocrinus, 

 Bathycrinus, and Hyocrinus, and there are several others. 



From the nature of the case, little can be known with regard to crinoids in 

 the living condition. Their food consists, however, of pelagic organisms and minute 

 crustaceans, and, as a rule, the largest supply of this nutriment is obtained by those 



