42 PHYLOGENY OF FUSUS AND ITS ALLIES. 



Three spirals enter into the composition of the tuberdes. The primary 

 and secondary spirals have a uniform size in the adult portion of the 

 shell. 



An unlabeled specimen in the collection of the Museum of Com- 

 parative Zoology (cat. 891) represents a dwarfed form of this species. 

 The spire is somewhat more slender and the knobs are somewhat 

 smaller than in the normal form. Gerontic features, such as rounded 

 whorl, crowded lines of growth, strong posterior canal and loose inner 

 lip, appear fully a whorl earlier than in normal individuals. The spirals 

 are like those of the normal form, being closely crowded and grooved, 

 so as to appear compound. 



The differences between this species and F. nodosa plicatns are given 

 by Dunker as follows (p. 99) : 



"A Fuso (Murice) longissimo Gmel., haec nostra species statura 

 multo minore, rostro breviore, costis spiralibus crassioribus minus 

 acutis costisque tuberosis facile distinguenda est. Praeterea anfractus 

 sutura multo profundiore disjunguntur." 



Localities: East Indies (Nat. Mus. 73156, 7377) ; Indian Ocean 

 (B. S. 226); Amboyna (B. S. 6079). 



FUSUS UNDATUS (Gmelin). 



17S0. Fusus longissimits glabratus angtilosus Chemnitz, Conch. Cab., vol. 4, p. 



183, tab. 145, fig. 1343- 

 1788. Miirex undatus Gmelin, Linn. Syst. Nat., ed. 13, torn, i, pars VI, p. 3556. 

 1822. Fusus incrassatus Lamarck, An. sans vert., T. VII, p. 124. 

 1842? Fusus longissiinus var. incrassatus Lamarck, Kiener, Iconographie, p. 4, 



pi. Ill, fig. I. 

 1847. Fusus undatus Reeve, Iconica, sp. 12. 



This species is the immediate successor of F. longissinins. The spire 

 is long and slender as in the most elongate individuals of F. tuhcrcidatus. 

 The early whorls are of the titrricuhis type, round and furnished with 

 round ribs. This is succeeded by a stage in which the young shell 

 has all the characters of a F. tuherculosus. This is generally quite 

 short, and is succeeded by a stage in which the characters of the im- 

 mature shell are those of an adult F. longissimus. The ribs increase 

 in prominence on the keel and finally become so strong as to affect 

 shoulder and body alike, producing the strong undulations so char- 

 acteristic of this species. In this last typical stage of the species the 

 keel appears bulbous from the excessive development of the tubercles. 

 Intercalated spirals appear in the sixth or seventh whorl, sometimes 

 earlier. 



A specimen in the collection of the Boston Society of Natural 

 History (cat. 223) represents a rather strongly modified variety of 

 this species. The early whorls are round, furnished with round close- 



