[SYSTEM]
You are answering a single information-extraction question. Use ONLY the supplied source material. Do not use prior knowledge. Give a clear, concrete answer with the specific number, name, year, or value asked for.

[USER]
--- SOURCE ARTIFACT (M3-L4) ---
# Table 123 — TaBLE VII. OCCURRENCE OF THE NAUPLII OF PELTOGASTER AND SACCULINA

PDF page: 512

```csv
Month,Nauplii recorded SS =.Peltogaster,Nauplii recorded SS =.Sacculina
February (1946),4,4
March,fe),10
April,fe),fo)
May,12,fe)
June,4,fo)
July,19,I
August,A,fe)
September October,2 fo),fe) 5
Septembe October,2 fo),fe) 5
November,fe),23
December,6,37
January (1947),8,24
ebruary arch,29 10,34 fe)
ebruar March,29 10,4 fe)
```

--- END ARTIFACT ---

Question:
Table VII in Vol 27 records monthly occurrences of Peltogaster nauplii per sample. The table includes a count for February 1946 and a count for May 1946, but provides no entries for March or April. Estimate the expected monthly count at the midpoint of the February-to-May period (i.e. midway between February and May) by linear interpolation between those two endpoints.

Answer concisely. Cite the row/cell/section you used. State your final numerical answer clearly.