586 SUMMARY OF CURRENT RESEARCHES RELATING TO 



missure is excessively shortened. These last two forms, with the 

 Solenoconcha, are euthyneural, but are all to be distinguished from 

 the Gastropoda by their remarkable retention of bilateral symmetry, 

 while each shows its own distinctive characters. Everything, how- 

 ever, points to the fact that all the groups here included under the 

 Mollusca, and whatever their special difference, have a common 

 ancestor and present a common tyj)e. 



New and Rare Cephalopoda.* — Professor Owen has published an 

 illustrated memoir, the concluding portion of which deals with 

 " Cephalopods remarkable for large size ; " Pledoteuthis grandis must 

 have had a total length of 33 feet. After discussing the evidence on 

 the subject, the author concludes that sufficient " has been obtained to 

 demonstrate that the greatest bulk in the molluscous sub-kingdom is 

 attained by members of its most highly organized class ; " and he 

 points out that in past times there were also great variations in the 

 size of the lower or tetrabranchiate order of Cephalopods ; their shells 

 ranged in size from those no larger than a modern Spirula to an 

 Ammonite four feet, and an Orthoceratites six feet in length ; and the 

 " constructors and occupants of such shells may have approached in 

 size to the larger naked Cephalopods recorded in the present paper." 



Giant Squids| — If any doubt still remained as to the real 

 existence of ArcMieuthis, the matter might now be regarded as 

 definitely settled, for Professor A. E. Verrill reports that in October 

 1875 there were, as he learns, a large number dead or dying cast 

 upon the Grand Banks; of these the fleet from Gloucester, Mass., 

 obtained between twenty-five and thirty, which they used as bait for 

 cod. They were, without the arms, 10-15 feet long, and 18 inches in 

 diameter. The arms were almost always mutilated, but the part that 

 remained was three to four feet long, and about as large as a man's 

 thigh. " One specimen, when cut up, was packed into a large hogs- 

 head tub, having a capacity of about 75 gallons, which it filled. 

 This tub was known to hold 700 lbs. of codfish. The gravity of the 

 ArchiteutJiis is probably about the same as that of the fish. This 

 would indicate more nearly the actual weight of one of these creatures 

 than any of the mere estimates that have been made, which are 

 usually much too great. Allowing for the parts of the arm that had 

 been destroyed, this specimen would, perhaps, have weighed nearly 

 1000 lbs." One was taken with arms 36 feet long. 



Ink-bag of the Cephalopoda.;}: — M. P. Girod finds that in Loligo 

 vulgaris this bag is much less developed than in Sepia officinalis, 

 though it presents the same general characters. The gland has the 

 form of a Phrygian cap, and at the upper part of its free edge has an 

 orifice, by means of which it communicates with the reservoir. In 

 Sepiola Bondeletii the bag is either simple or trilobed ; in the latter 

 case there is on either side an elongated body which is connected by 

 a constricted portion with the central mass, the presence of which 



* Trans. Zool. Soc. Loud., xi. (1881) pp. 131-70 (13 pis.), 

 t Amer. Journ. Sci., xxi. (1881) pp. 251-2. 

 j Comptes Rendus, cxii. (1881) pp. 966-8. 



