EAST COAST MARINE SHELLS 



149 



'Twas the Dana Expedition 

 That discovered Spirilla's home 



Far above the oozy bottom 

 And below the great waves' comb; 



For bathypelaglc is the Spirula 

 And there's where it loves to roam. 



It only lives in the warmer seas. 



At more than a thousand feet. 

 Suspended head down in the water 



A position hard to beat- 

 Though doubtless it is its chambered 

 shell 



That aids it in this feat. 



And now they say that the "sucking disk" 



Is really a lamp instead. 

 And perhaps its lighter color is due 



To its standing on its head: 

 But, alas! poor little Spirula 



Can't rest in the ocean's bed." 



ORDER OCTOPODA 



Family Argonautidae 



Male very small, without arms or 

 shell; female provided with a symmetrical 

 shell which is secreted by thin terminal 

 expansions of the two dorsal arms. All 

 other molluscan shells are secreted by the 

 mantle but Argonauta uses its arms to per- 

 form this function. 



Prior to the year 1839 two eminent 

 naturalists of their day. Gray and de 

 Blainville, advanced a fantastic theory 

 with respect to the animal of Argonauta. 

 Their strange hypothesis maintained that 

 the inhabitant of the "Paper Nautilus" was 

 a parasite Incapable of producing a pro- 

 tection of its ovm while the original 

 builder was a Heteropod. 



In 1839 Madame Jeannette Power 

 working in her vivarium at Messina, Sicily, 

 made a series of observations upon Argonau- 

 ta. She demonstrated that the yoimg when 

 first excluded from the egg is naked, and 

 that after ten to twelve days the shell be- 

 gins to appear being deposited by the two 

 web-like arms and that when broken it is 

 repaired through the same agent. 



The shell is thin and translucent, 

 not shaped to conform to the body of the 

 animal nor attached by shell muscles. The 

 hollow of the spire, not occupied by the 



animal, provides a repository for the eggs, 

 also a protection and serves in their in- 

 cubation. It is nearly equivalent to the 

 float in Janthina. The Argonauta literal- 

 ly sits in its boat with the sail-shaped 

 arms close to its sides and used as oars. 

 Propulsion is accomplished by ejection of 

 water from the funnel but when crawling it 

 assumes a reversed position with the shell 

 upon its back like a snail (Power and Rang). 



The male Argonauta is said to be 

 only an inch in length and provided with a 

 sac in the form of a separate arm which is 

 used in mating time. 



GENUS ARGONAUTA Llnne 1758 

 (ARGONAUTS) 



ARGONAUTA ARGO AMERICANA Dall. The well- 

 known "Paper Nautilus." The specimen fig- 

 ured is abnormal in that a break in the 

 shell necessitated a resumption of con- 

 struction on the outer edge which resulted 

 in a break of the continuity. Average 

 length 5 inches. 



This fine shell Is often taken on 

 the beaches of Florida after winter storms, 

 sometimes containing the animal. Depth 

 range 0-1917 fathoms. 



PI. 28, Fig. 2 



PI. 66, Fig. 1, la, lb 



Massachusetts to West Indies; warm 



oceans generally. 



ARGONAUTA GONDOLA Dillwyn (A. hians 

 Solander). Shell with few, well-separated, 

 ribs; surface smooth, polished. The speci- 

 men illustrated measures 28 mm. and was 

 taken at Boynton, East Florida. 



PI.' 28, Fig. 3 



South Atlantic; Pacific 



Family Octopodldae 



Among the Cephalopoda the Octopus 

 stands at the head being the most highly 

 developed, possibly, of all mollusks. It 

 presents a decided contrast to the other 

 sedentary and harmless mollusks which be- 

 long to the other great classes. Fig. 54. 



The Octopus is indeed the pirate 

 or outlaw of the sea. It usually lives in 

 some rocky hole, the approaches to which 

 are often strewn with the bones or remains 

 of its victims. The suckers are used for 

 attachment to its prey and also to prevent 



