“s Trans. Acad. Sci. of St. Louis 
seen. The normal shell of a mature specimen of T. 
portoricensis is smaller than that of T. bartschi. The 
length of the apophysis always proportionately less. 
The partitions in the tube, while always present, are 
much lower and shorter than in 7. bartschi. The pallets 
resemble those of 7. bartschi, but constantly differ from 
them in having the blade longer and narrower, the june 
ture of the blade and pallet hardly perceptible, and 
the basal portion of the blade more gradually expanded. 
Seen through the periostracum, the calcareous portion 
of the blade of the pallet of 7. bartschi appears cone 
shaped, whereas that of T. portoricensis is the opposite, 
being deeply cupped at the center. In T. portoricensis 
the periostracum on the outer face of the blade is less 
deeply cupped than that on the inner, while in 7. bartscht 
the reverse is true. 
This species has been found in the test-blocks placed 
by the Committee on Marine Piling Investigations, at 
the following locations: Guantanamo, Cuba; San Pedro 
de Macoris, Santo Domingo; Port au Prince, Haiti; San 
Juan, Porto Rico; St. Thomas, Virgin Islands; Coco 
Solo, Panama, and (one specimen) Key West, Florida. 
At Guantanamo, Cuba, wood placed in the water on 
April 10th, contained specimens 10 mm. in length on 
May 10th; 60 mm. in length on June 10th, and 75 mm. 
in length July 10th. 
At Port au Prince, Haiti, wood submerged December 
1, 1922, contained on January 1, 1923, many 5 mm. spec 
imens; on January 15th, 30 mm. specimens, and, on Feb- 
ruary Ist, 30 mm.:specimens with the gills well filled 
with many fully developed embryos. Wood placed in 
the water at this location on June 1, 1923, although well 
filled with several other species of shipworms, contained 
